Emma Raducanu shone at a grand slam again as she marked her Australian Open debut with victory in the battle of the US Open champions against Sloane Stephens.

The 19-year-old has found wins hard to come by since her extraordinary success in New York in September but, back on the big stage, Raducanu came up with the right formula again to claim a 6-0 2-6 6-1 victory.

She lost just four points in a startling first set that admittedly was woeful from Stephens before the American hit her stride in the second.

That set up a first-ever decider at this level for Raducanu, and she could not have handled it any better, keeping her cool and striking the ball with confidence to clinch victory after an hour and 45 minutes.

Raducanu, who will take on Danka Kovinic next, said: "I just want to thank everyone for coming out and staying so late.

"Both me and Sloane really put everything out there. I thought it was a really high-quality match with lots of great rallies so I'm really happy to have come through against such a great champion.

"It was a tough match-up for a first round. Her athleticism is really up there. I was having to work extremely hard for my points but I'm so happy to have got through.

"I was very pleased.

"Coming out for the first set, I thought I played some very good tennis. Of course there was going to be some adversity.

"I'm happy to have regrouped. In the third I don't think the score really reflected it. I was really feeling it."

There will be no Australian Open fairytale for Leylah Fernandez this year after a bad day at the office saw the Canadian teenager bundled out in the first round by Maddie Inglis.

Maddie Inglis shakes hands with Leylah Fernandez after winning her first round singles match

The 19-year-old's run to the US Open final against Raducanu was one of the stories of last year but Melbourne Park is not a happy hunting ground for her.

The 6-4 6-2 loss to the Australian wildcard marked the third straight year Fernandez had fallen at the first hurdle at the year's opening Grand Slam.

"Too many mistakes," said Fernandez. "I'll give credit to Maddie. She played a great match from beginning to end.

"Now it's just get back on the practice court, get ready for the next tournament and the next match and see how it goes on the next Grand Slam."

Inglis seized the advantage with a break in the seventh game to take the opening set and then opened up a 4-0 lead in the second with a double break.

Fernandez, who accumulated 30 unforced errors, had two of her three breakpoint opportunities in the sixth game of the second set, but failed to convert as Inglis stayed solid to secure victory on her third match point.

"Today was just a bad day in the office," the 23rd seed added. "The solutions that I was trying to come up with, I was making mistakes and just wasn't a good day today."

Inglis had lost her previous two meetings with Fernandez and Tuesday's victory was her first in the main draw of a Grand Slam in five attempts.

"I had thought of that moment for a long time. It was just pure happiness," the 24-year-old from Perth said of her emotions after Fernandez sent a forehand long on match point.

"I'm really so happy I could have it here in Melbourne with all my friends and family there. It was incredible. Really lucky."

Iga Swiatek won 11 games in a row to defeat Britain's Harriet Dart in the first round.

Dart came through qualifying for the third time here in four years, and for the third time found herself on Rod Laver Arena facing one of the big names.

She suffered the dreaded double bagel against Maria Sharapova in 2019 before a much better performance against Simona Halep the following year.

Dart, ranked 123, made a good start against seventh seed Swiatek, leading 3-1, but the Pole began to cut out the errors and, despite not doing too much wrong in the second set, the British number three failed to win another game.

Heather Watson gained her first grand slam victory in a year with a three-set success over Mayar Sherif of Egypt.

Wins have been hard to come by recently for Watson but she ended a seven-match losing run dating back to August in Adelaide last week and carried that confidence into Melbourne.

She is now ranked down at 94, 32 places lower than Sherif, who has been heading in the other direction.

But Watson played a fine match to win 6-3 5-7 6-2, thumping 40 winners and putting aside the disappointment of losing the second set.

Additional reporting: Reuters