Serena Williams extended her US Open farewell with a gritty opening win on an entertaining night packed with hope and celebration in New York.

A near-capacity 25,000 crowd on Arthur Ashe Stadium willed on their idol, who responded in typical determined style.

Williams, 40, will play Estonian second seed Anett Kontaveit in the second round on Wednesday.

The 23-time Grand Slam singles champion, who is one short of Australian Margaret Court's all-time record, is also playing in the doubles alongside older sister Venus, adding another exciting element to what she hopes will be a long goodbye this fortnight.

Her first assignment was beating Kovinic, ranked 80th in the world, and there was a thunderous noise when she took the first of three match points to ensure her singles career was not over yet.

Williams jumped on the spot when Kovinic's backhand return hit the net, then twirled ecstatically in the centre of the court before blowing kisses to her adoring fans when she had returned to her seat to soak in the occasion.

On how occasions like this affect her plans, she said: "It's extremely difficult still because I absolutely love being out there.

"The more tournaments I play, I feel like the more I can belong out there. That's a tough feeling to have, and to leave knowing the more you do it, the more you can shine.

"But it's time for me, you know, to evolve to the next thing. I think it's important because there's so many other things that I want to do."

Williams thrills crowd on night of celebration

Williams has long been more than a tennis player and it was a sign of her status - as an American icon and one of the world's most recognisable sport stars - that she announced her retirement in an essay for glossy fashion magazine Vogue.

Although the former world number one did not use the word retirement itself, preferring to say she was "evolving away" from the sport, there is no mistaking her intention is to end her glittering career this fortnight at her home major.

Suitably, for what could have been her final match, it was a night of celebrity and glamour.

Williams - wearing a glittery, figure skating-inspired dress and diamond-encrusted trainers to add further theatre to the occasion - unsurprisingly arrived on court to a rapturous reception, moments after the stadium watched a video montage in celebration of what she has achieved as a player and a person.

"When I walked out, the reception was really overwhelming. It was loud and I could feel it in my chest. It was a really good feeling," she said.

"It's a feeling I'll never forget. It meant a lot to me."

Kovinic had already come out to court, leaving her with a long - and what must have been a nervous - wait next to her chair.

Film director Spike Lee, who called Williams his "little sister" in a video released earlier on Monday, took part in the coin toss, while Vogue editor Anna Wintour, another close personal friend, was sat in her support box behind the player's family.

Other famous faces picked out by the stadium cameras included former US President Bill Clinton, soul singer Gladys Knight, boxer Mike Tyson and model Bella Hadid.

Williams' daughter Olympia, wearing white beads in her hair in a tribute to her mum's style when she won the 1999 US Open, sat on the front row, alongside her dad Alexis and in front of grandmother Oracene.

The entire family jumped to their feet when Williams clinched a victory which will long live in the memory for those who saw it.

But it was not over quite yet. Television host Gayle King came out on to the court to lead another celebration, firstly joined at the microphone by Billie Jean King - another pioneering American tennis legend, who paid a warm tribute - and then Williams herself.

"I didn't expect any of this," Williams said. "I always have to do the best that I can. I have always felt so comfortable here.

"The crowd was crazy! It really helped pull me through. I was really pumped. I thought 'I got this'."

How far can Williams go?

After all the fanfare, the serious business of the tennis began and Williams showed all of her competitive nature in a match that lacked quality for most parts.

Both players looked overawed by the occasion, producing lots of double faults and unforced errors in a scratchy first set, before Williams eventually took control.

There had been doubts about what condition she would be in, having struggled with a knee injury before being thrashed by British number one Emma Raducanu in Cincinnati.

Williams, now ranked 413th in the world, started positively as she moved into a 2-0 lead before Kovinic fought back for a 3-2 advantage to dampen the mood on Ashe.

But the American won the final four games to clinch the opening set and spark more jubilant scenes.

The second set ominously started with Kovinic hitting another double fault and although she recovered to hold, Williams continued to put her serve under pressure.

Once Williams broke for a 3-2 lead, it did not feel like she would surrender the lead. As she headed towards victory, the veteran was moving well, hitting well and showed plenty of quality.

Now there will be another night of intrigue when she comes up against Kontaveit.

The Estonian is ranked second in the world and, even though she has not lived up to that status this year, losing to Williams would send seismic shockwaves throughout the sport.

It would also increase the hope of some American fans who are dreaming - more through emotional nostalgia than reasoned judgment - that their idol can somehow win that elusive 24th major and bow out spectacularly by equalling Court's all-time record.