British number one Cameron Norrie says he does not know why he "didn't perform and didn't execute" as the nation's bid in the Australian Open singles made an inauspicious start.

The 26-year-old looked a shadow of the player who enjoyed a stellar 2021 as he lost 6-3 6-0 6-4.

"It is so disappointing to start the year like this," he said.

"I was never really in the match at all. I played a loose game at the start of every set and he took care of his serve very well.

"I am disappointed with my level throughout."

Six more Britons, led by Emma Raducanu and Andy Murray, play on Tuesday.

Dan Evans, Heather Watson, Harriet Dart and Liam Broady, who qualified for the men's draw for the first time in his career, are also in action.

Norrie to tailor schedule after Melbourne disappointment

Norrie soared up the rankings after a breakthrough 2021 season where he won the prestigious Indian Wells title and reached the season-ending ATP Finals as an alternate.

Deep runs at a Grand Slam are yet to follow, however. Norrie has never gone past the third round of a major in 17 main-draw appearances.

Norrie won 52 of his 87 matches in a busy and successful 2021, but plans to tailor his schedule more this year in order to improve his record at the Slams.

"I will try to peak more for the bigger tournaments. But first I will have to win some tour matches, otherwise I will be feeling fresh and leaving Slams disappointed - like I am now," he told BBC Sport.

Preparations for the start of the new season were disrupted by testing positive for Covid-19, leaving Norrie unable to practise for a week around Christmas.

The left-hander acknowledged the episode left him losing "a bit of rhythm", but says it has not contributed to starting the 2022 season with four successive defeats.

"I feel great physically and mentally. It was not unbelievable preparation but I feel good," he added.

"I had ATP Cup matches to play, then a week off and it was perfect preparation for me. I just didn't perform and didn't execute."

Korda, runner-up at the 2021 Next Gen ATP Finals, is rated as one of the hottest prospects in the men's game. He too had his preparations derailed by Covid.

A positive test when he arrived in Adelaide on 6 January meant he had to quarantine and, while he had no symptoms, he was left hitting balls against the wall of his hotel room.

Questions were raised about Korda's condition going into the opening Grand Slam of the season, but the 21-year-old answered them emphatically to record his first main-draw win in Melbourne.

He will play Frenchman Corentin Moutet in the second round.

Analysis - 'Norrie's pre-season can now begin'

BBC tennis correspondent Russell Fuller at Melbourne Park

Cameron Norrie says he didn't perform, and he didn't execute - and he does not know why.

A December bout of Covid, with the accompanying isolation, clearly did not help, and having the season of your life can also have some short-term repercussions.

Norrie played 77 matches last year, won Indian Wells in October, made two appearances as an alternate at the ATP Finals and finished his season at the Davis Cup on the final day of November.

Very, very few can just keep on playing relentlessly at that level. If you are successful, and good enough to play both Davis Cup and the season-ending championships, there is not an off-season worthy of the name.

But at least after four defeats out of four in Australia, pre-season can now begin. Norrie plans to do a two-week fitness block before playing indoors in Rotterdam in February.

As for Sebastian Korda, he is now eyeing a long run in Melbourne. What a performance it was in his first match of the season, having spent seven days in isolation in his Adelaide hotel room.