Serena Williams branded her performance in the US Open final "inexcusable" and said it was the "worst match" she played during the tournament.

Williams, who turns 38 later this month, was beaten 6-3 7-5 by Canadian 19-year-old Bianca Andreescu, whose win marked her first Grand Slam title.

Defeat means American Williams is still chasing a record-equalling 24th major.

"I believe I could have just been more Serena today," said Williams, a six-time champion at Flushing Meadows.

"I honestly don't think Serena showed up. I have to kind of figure out how to get her to show up in Grand Slam finals.

"It's inexcusable for me to play at that level."

Andreescu, in the main draw in New York for the first time, dominated a 43-minute opening set to stun a partisan Arthur Ashe Stadium, going a break up in the very first game.

The 15th seed held match point at 5-2 in the second set before Williams staged an attempted comeback, winning five successive games.

"I was just thinking, honestly at that point, wow, this is terrible," said Williams. "Like you got to play better. I have to do better.

"I just couldn't go down like that, so I just wanted to play a little bit better."

Andreescu broke Williams' serve for the fourth time of the set to wrap up the win, making her the first Canadian to win a Grand Slam singles title and the first teenager to do so since Maria Sharapova at the 2006 US Open.

Williams remains on 23 Grand Slam titles, one short of Australian Margaret Court's all-time record.

"I'm not necessarily chasing a record. I'm just trying to win Grand Slams," Williams said.

"It's definitely frustrating. But for the most part I just am still here. I'm still doing what I can do."

'I'm so close, yet so far away'

Williams has now lost her last four Grand Slam finals, last winning in Australia in 2017 before the difficult birth of her daughter later that year.

In 2018, she lost the Wimbledon final to Angelique Kerber before a controversial US Open final defeat by Naomi Osaka, and was beaten in this year's final at the All England Club by Simona Halep.

Williams said her successive falls at the final hurdle were "truly frustrating" but vowed to keep going.

"Kerber doesn't count because I was exhausted," she said. "My baby was eight months, and that's tough.

"But all of it honestly, truly is super frustrating. I'm so close, so close, so close, yet so far away.

"I guess I've got to keep going if I want to be a professional tennis player. And I've just got to just keep fighting through it.

"I definitely did better than I did against Halep."

Three years ago, a 16-year-old Bianca Andreescu wrote herself a fake cheque.

That cheque was a mock-up of the one given to the US Open champion.

Now, after beating the great Serena Williams 6-3 7-5 in Saturday's compelling final, the composed Canadian is ready to cash a real one worth about £3.1m.

"I've been dreaming of this moment for the longest time," the 19-year-old said of winning her first Grand Slam title, wiping away tears as the magnitude of what she had just achieved finally hit.

"For it to become a reality is crazy."

Crazy is a word which Andreescu, like most teenagers, readily uses to describe unexpected situations and one which has cropped up regularly in her chats with the media over the past few days.

Not without good reason.

Twelve months ago and struggling with injury, she lost in the first round of qualifying at Flushing Meadows and was ranked outside of the top 200 in the world.

But she has become one of the most talked-about young players on the planet following a remarkable rise this year.

Andreescu, whose Romanian parents Nicu and Maria emigrated to Canada in the 1990s, had only played six tour-level matches at the turn of the year.

Since then she has won prestigious WTA Premier titles at Indian Wells and Toronto, rising to 15th in the world as a result and raking in £1.79m of her £1.97m career prize money.

Now the gains are even higher after becoming a Grand Slam champion: she will climb to fifth in the world, take home a winning prize of £3.13m and, surely, become a face recognised by many outside of the parameters of Canada and tennis.

"I never really thought about being famous. I'm not complaining though," she smiled.

"My goals have been to just win as many Grand Slams as possible, become number one in the world. But the idea of fame never really crossed my mind.

"It's been a crazy ride this year. I can definitely get used to this feeling."

And the prize money? "Don't ask me that because I have no clue. I've never held that much money in my life!"

Succumbing to the trappings of fame and wealth at a young age looks unlikely for the warm teenager, who has been nurtured by father Nicu, an engineer, and mother Maria, a chief compliance officer for a finance firm.

Maria herself has become a popular figure, particularly among social media users, thanks to her striking look, bold fashion statements and as she brings Coco, Andreescu's pet dog, to sit on her lap during matches.

Andreescu, an only child, describes her as "the coolest person I know and my role model".

She also has her mum to thank for helping develop the mental resilience which she needed to block out a passionate home crowd at Flushing Meadows as Williams threatened to derail her hopes.

"I started meditating and visualising ever since I was 12 or 13 when my mum introduced it to me, and I know it wasn't such a big thing back then, but now it's getting more popular because I think if you can control your mind, then you can control a lot of things," she said.

"I think that's what's been working really well for me. I just kept doing that.

"When I'm on the court in front of these big stages, I'm really good at just blocking everything and staying in the zone."

Belief is not something Andreescu has in short supply, illustrated by the way she struts around the court - even on the cavernous Arthur Ashe Stadium, even in her first Grand Slam final - with her head always up.

And that confidence exudes in a marvellous all-round game which has the variety to pull opponents apart, as well as having a killer forehand already rated as one of the best in the game.

Williams, the 23-time Grand Slam champion rated as the greatest female player ever, could not cope with the teenager's consistent depth as she was hustled out of a record-equalling major.

"I feel like Bianca plays well under pressure. She goes out and she plays hard," the 37-year-old said.

"She does what she does best, and that's move up to the ball, that's hit winners, that's play with a ton of intensity."

Andreescu had already earned six wins over top-10 players this year - Caroline Wozniacki, Elina Svitolina, Angelique Kerber (twice), Kiki Bertens and Karolina Pliskova - going into Saturday's final.

And Williams, who she led against in their Rogers Cup final in Toronto last month before the American retired with a back injury, became the latest victim.

This run to the US Open title means Andreescu has won 14 straight matches and an extraordinary 45 of her 49 matches this season.

She is the first teenager to lift a Grand Slam singles title since Maria Sharapova won the 2006 US Open aged 19 and matched Monica Seles' record of winning a major in the Open era on only her fourth appearance in a Grand Slam main draw.

While Andreescu's rise has been rapid, a dream-like year has also not been without its challenges.

She missed a large chunk of the season after suffering a shoulder injury at the Miami Open in March which, after an ill-judged attempt to play the French Open, forced her to miss the entire grass-court swing, making her swift ascent and formidable winning record even more remarkable.

"It's definitely a process of life. You're never going to have ups all the time," she said.

"So I think in those moments, you just have to deal with it the best that you can, which is to just keep fighting for your dreams and just stay as persistent and persevere as much as you can.

"I know in those moments you feel like you can't.

"But if you believe that there are good times ahead, then those tough moments are definitely worth it. I think it builds you as a character.

"I think everyone should go through it because it just makes you stronger."

Teenager Bianca Andreescu stunned Serena Williams in a gripping US Open final to claim a first Grand Slam title and deny the American a 24th major.

Williams, 37, did not cope with the 19-year-old's quality in a 6-3 7-5 loss.

Canadian 15th seed Andreescu, in the main draw here for the first time, blew a double break in the second set before taking her third match point and falling to the ground in disbelief.

"This year has been a dream come true," Andreescu told the crowd.

"I am beyond grateful and truly blessed. I've worked really hard for this moment. To play on this stage against Serena - a true legend of the sport - is amazing."

To the disappointment of a stunned home crowd on a passionate Arthur Ashe Stadium, Williams has now lost four successive major finals.

"Bianca played an unbelievable match," Williams said. "I'm so proud and happy for you, it was incredible tennis out there."

Williams, seeded eighth, looked edgy throughout as she aimed to match Australian Margaret Court's tally of all-time major wins, handing over the first three of Andreescu's five breaks of serve with double faults.

By contrast, Andreescu played with the confidence which has marked her out as a star in a stunning breakthrough year.

She is the first Canadian to win a tennis major and the first teenager to win a Grand Slam since Maria Sharapova claimed the 2006 title at Flushing Meadows.

She is the first teenager to win their maiden Slam since Russian Sharapova at Wimbledon in 2004.

Andreescu kept her nerve to take a third match point with a forehand down the line, dropping her racquet to the ground and then, after a warm hug with Williams, lying on the court with her arms spread out as she contemplated her achievement.

After returning to her feet, she used a hastily-arranged step ladder to climb into her player's box and embrace her nearest and dearest, including parents Nicu and Maria.

Andreescu blocks out crowd to complete remarkable year

Before the match, Andreescu said if someone told her 12 months ago she would be facing Williams in the US Open final she would have thought they were "crazy".

Tellingly, in a sign of her unwavering confidence, she said she would not have felt the same if they told her the same thing a fortnight ago.

Twelve months ago she lost in the first round of qualifying at Flushing Meadows and was ranked outside the top 200 in the world.

But she has become the most talked-about young player on the planet following a remarkable rise this year.

Andreescu, whose Romanian parents Nicu and Maria emigrated to Canada in the 1990s, had only played six tour-level matches at the turn of the year.

Since then she has won prestigious WTA Premier titles at Indian Wells and Toronto, rising to 15th in the world as a result and raking in £1.79m of her £1.97m career prize money.

Now she will climb to fifth in the world and take home another $3.85m (£3.13m) after this success.

Andreescu was fearless throughout her maiden Grand Slam final and unfazed by the occasion of playing an American icon on the biggest tennis court in the world.

Although the crowd was unsurprisingly backing Williams throughout inside an incredible noisy Ashe, the manner in which Andreescu coped and reset after seeing her double break in the second set disappear was remarkable.

At one point, Andreescu even put her fingers in her ears as the volume became particularly loud as Williams fought back from 5-1 down.

After her first Championship point went begging in the seventh game, another disappeared when Williams hit an ace for 30-40 in what proved to be the final game before Andreescu sealed victory at the third attempt with a forehand winner.

"I definitely had to overcome the crowd. I knew you guys wanted Serena to win," a smiling Andreescu said in her on-court victory speech.

"Obviously it was expected for Serena to fight back, but I tried my best to block everything out. I'm glad how I managed to do that."

Williams fails to get over the line again

Williams said after July's defeat in the Wimbledon final against Simona Halep that the weight of history was not a burden as she aimed to clinch that record-equalling 24th Grand Slam.

Yet, after also losing last year's Wimbledon final and a controversial US Open final against Naomi Osaka 12 months ago, this latest defeat inevitably leads to more questions about why she cannot get over the line.

With time seemingly running out for the six-time US Open champion, who turns 38 this month, it makes you wonder how many more chances she will have to earn her place as the greatest ever, at least in numerical terms.

However, BBC Radio 5 Live analyst Jeff Tarango is in no doubt she will reach more Grand Slam finals.

"I think Serena will pull it together. I don't have any doubt. She's going to be back, she's not going to give up," the American said.

If Williams was looking for a comfortable start following her three previous final defeats, that did not materialise.

Nerves again seemed to take hold as she produced two double faults to gift the opening game to Andreescu, leaving her chasing a deficit which she could not recover.

It was the first break point she had faced - and lost - since the first set of her fourth-round win over Croat Petra Martic.

The confidence she showed in the routine wins over China's 18th seed Wang Qiang and Ukrainian fifth seed Elina Svitolina were not apparent as Andreescu's depth and variety, plus her ability to absorb Williams' power, unsettled the American.

Williams, who had close friend Meghan Markle, the Duchess of Sussex, sitting with her family, could not play with the control she showed against Wang and Svitolina, producing 14 unforced errors in a loose opening set.

All of her nine previous defeats in Grand Slam finals came after losing the opening sets and this miserable record did not look like changing when Andreescu started racing away with the second set.

Williams looked dejected as she continued to struggle to land a first serve, regularly looking at her racquet and shaking her hand as though she had no answers.

Suddenly she started to provide them in a spirited fightback, only for two more unforced errors to creep in to stall her momentum as Andreescu broke for a sixth time.

"I was just fighting at that point [at 5-1 down in the second set], trying to stay out there a little bit longer. The fans started cheering so hard and it made me feel better and fight a bit more," Williams said.

"Bianca played an unbelievable match. If anyone could win this, outside of [sister] Venus, I'm happy it's Bianca."

'Andreescu is the real deal' - reaction

Tennis great Billie Jean King: "Congratulations to Bianca Andreescu on winning her first major title at the #USOpen. She is Canada's first Grand Slam singles champion! The Future is now. A phenomenal effort by Serena Williams until the very end.

2019 Cincinnati Masters champion Madison Keys: "Congrats Bianca Andreescu on your first Grand Slam. So happy for you! Always a fighter, always inspiring - win or lose Serena Williams. Such a great match to watch."

Wimbledon champion Simona Halep: "Congratulations Bianca Andreescu on an amazing performance and your first Grand Slam! Romania is very proud of you."

Canadian Prime Minister Justin Trudeau: "Congratulations Bianca Andreescu! You've made history and made a whole country very proud."

BBC Radio 5 Live tennis commentator David Law: "Andreescu was just magnificent for the first set and a half. We ran out of superlatives to describe the way she was playing. She has presence and buckets and buckets of ability. It's remarkable to see it in a 19-year-old. She is totally unfazed by her surroundings, it would appear. That is four Grand Slam finals in a row that's Williams has not been able to win, but I don't know how much more she could have done today. Andreescu is the real deal."

Rafael Nadal will move within one of Roger Federer's haul of 20 Grand Slam titles if he beats first-time major finalist Daniil Medvedev in Sunday's US Open showpiece.

Second seed Nadal, 33, is the favourite to win his fourth title in New York.

Russian fifth seed Medvedev, 23, has lost just two of his past 22 matches, including a defeat by Nadal in August's Rogers Cup final.

"I would love to be the one who wins more Grand Slams," Spaniard Nadal said.

But he added: "I still sleep very well without being the one who has more Grand Slams."

Medvedev, the first Russian man to compete in a Grand Slam final since Marat Safin at the 2005 Australian Open, is aiming to break the grip of Nadal, Federer and Serbian world number one Novak Djokovic on the majors.

The 'big three' have won each of the past 11 Grand Slam titles, with Stan Wawrinka's victory here in 2016 making the Swiss the last man outside the illustrious trio to claim one of the sport's biggest prizes.

He will face Nadal for the second time in less than a month after the world number two won 6-3 6-0 in Montreal.

"It's great that I have this experience playing Rafa in the final of a Masters. I know what to expect. I know how to prepare for it," Medvedev said.

'This is just one more chance to catch Roger'

Nadal, who won his 18th Grand Slam with a 12th title at Roland Garros in June, was already considered one of the favourites in New York from the start of tournament, along with Djokovic and Federer.

That has been a familiar pattern over the past decade such has been the trio's dominance, which shows no signs of changing despite all three men entering their 30s.

The past 11 Grand Slams have been won by Nadal, 32-year-old Djokovic or 38-year-old Federer.

But the departure of 2018 champion Djokovic, who retired from his last-16 match against Stan Wawrinka with a shoulder injury, and Federer's quarter-final exit to Bulgarian world number 78 Dimitrov, has given the opportunity for Nadal to make a serious move in the race to be considered the greatest player of all time.

If Nadal lifts his fourth title at Flushing Meadows, he will move within one of Federer's tally for the first time.

"I always say the same: we still playing. Here we are," said Nadal, who will be competing in his third Grand Slam final this year and also reached the Wimbledon semi-finals.

"When I arrived here, my goal was to produce a chance to compete for the big thing again. Here I am.

"I have given myself another chance, as I did in Wimbledon, as I did in Australia, as I did in Roland Garros. That's the personal satisfaction. That's the personal happiness.

"I am happy about my career. I am very happy about what I'm doing. I'm going to keep working hard to try to produce chances.

"Sunday is just one more chance, that's all.

"If I am able to win on Sunday, it will be amazing. If I lose, I hope to keep having chances in the future to add things."

Medvedev doesn't want 'amazing' summer to end badly

Medvedev came into the final Grand Slam of the season as the form player on the ATP Tour after an impressive build-up on the North American hard courts.

The Russian, who broke in the world's top 10 for the first time in July, lost to Australian Nick Kyrgios and Nadal in the Washington and Montreal finals before going one better by beating Belgian David Goffin in the Cincinnati final.

And he has continued that form to become only the third man to reach all four finals in the same season during the Open era.

"This summer has been so fast and long at the same time," Medvedev said.

"Long because I've played so many matches. At the same time so fast because I haven't had any moment to just sit down and look back and say I've done amazing things.

"Hopefully I will have some time after Sunday. It's going to be the last match in the United States this summer.

"Of course, deep inside of me, I understand that what I've done these four weeks is amazing, even comparing to what I've done before.

"I don't want to stop. I will always work to be better. I will try to do my best every day."

Despite his success, some of Medvedev's actions over the past two weeks have not endeared him to the New York crowd, goading them with his provocative post-match celebrations and interviews.

Since being booed off court after his third-round and fourth-round wins, Medvedev has looked to shake off the role of pantomime villain and apologised for his behaviour, which has included angrily snatching towels from ball people and curtly 'thanking' the American fans for jeering him.

"I can only say I'm a really calm person in life. I actually have no idea why the demons go out when I play tennis," he said.

"Every time I do something wrong on the court, I'm sitting with myself, thinking 'I'm not like this in normal life. Why does it happen? I don't want it to happen like this'.

"So I have been working a lot on it, and I have improved a lot. Sometimes it still happens.

"But, talking about normal life, to make me angry you need to do something crazy for one week in a row.

"You need to, I don't know, come to my hotel, knock on my door at 6am in the morning for seven days in a row. Then I'm going to be maybe mad a little bit. If not, I'm really calm."

"The bigger the occasion, the bigger she hits," Bianca Andreescu's coach said before the Canadian's US Open final victory.

Sylvain Bruneau was talking about the 19-year-old, but it could have equally applied to Serena Williams, her opponent, at pretty much any point over the past 20 years.

But something has changed in Grand Slam finals of late.

For Williams to reach the 2018 Wimbledon final, just 10 months after her traumatic experience in labour, was nothing short of miraculous. And for the American to do the same at last year's US Open, with very few matches in between, was another phenomenal feat.

Angelique Kerber and Naomi Osaka played extremely well to win those finals, Simona Halep was exceptional in this year's Wimbledon final, and the poise, belief and skill of Andreescu at Flushing Meadows on Saturday was quite something to watch.

A growing group of players now believe they have what it takes to beat the 23-time Grand Slam champion - who is one short of Australian Margaret Court's all-time record - when a trophy is on the line.

Williams, 37, may think she has the beating of them, but it does not appear that way, and she did not play nearly as well in the final as she had done in earlier rounds.

Her movement, so impressive in the semi-finals against Elina Svitolina, was much more laboured. And her serve was much diminished.

Williams was broken three times in six matches before the final. On Saturday, she was broken six times in two sets.

She made just 44% of first serves. She won only 30% of her second-serve points. And she sent down eight double faults.

Her serve recovered, briefly, as she won four games in a row to level the second set to thunderous encouragement from the Arthur Ashe Stadium crowd.

Andreescu put her fingers in her ears to block out the noise but then, at 5-5 and with the Canadian only too aware a championship point had come and gone, the confident and clinical Williams disappeared.

Her serve and her groundstrokes became edgy and tentative, as Andreescu regained the composure which would earn her a richly deserved first Grand Slam title.

"Serena...," Williams said, addressing herself in a post match news conference. "You didn't miss a serve, you lost serve maybe twice in the whole tournament, and you didn't hit a first serve in today.

"That was obviously on my mind. How do I play at a level like this in a final?"

The 2013 Wimbledon champion Marion Bartoli, a close friend of Williams, thinks the American puts extra pressure on herself, and cannot rid that from her mind when she steps on to court.

"She just feels she has to win this one, and it has to be that one that she's going to get to 24, and then to 25 [Grand Slam titles]," Bartoli told BBC Radio 5 Live last week.

Williams' next opportunity to draw level with Court's record will come at the Australian Open in Melbourne in January.

Winning a final on the WTA Tour between now and then might do Williams a power of good, but will she want to compete in Asia in the final stretch of the year?

She has not played any tournaments after the US Open for five years. In 2014, when she last played and won the WTA Finals, she went on to win the Australian Open, the French Open and Wimbledon the following year.

After 22 years on tour - and with a two-year-old child to consider - another spell away from home may not remotely appeal. But surely a few more tournaments, and the chance to play at least three matches against top-eight opponents at the WTA Finals in Shenzhen, would be an excellent springboard into 2020?

Williams, of course, has absolutely nothing to prove. To most, she is already considered the greatest of all time - in the women's game at the very least. She has been in Grand Slam finals 20 years apart, and has won all of her major titles in the Open era.

But she so desperately wants to equal, and then surpass, Court's tally.

Further opportunities may well arise, but it is now entirely reasonable to ask if, rather than when, she will do it.