Australian Open: World No 1 Iga Swiatek defeats former champion Sofia Kenin in round one

Kenin lifted her first major title here in 2020 before losing to Swiatek in the French Open final the same year but has struggled since with injuries and a loss of form.

The American remains a dangerous player, though, and knocked Coco Gauff out in the first round of Wimbledon last year.

She served for the opening set before Swiatek fought back to take it in a tie-break, and the Pole was the steadier in the second to claim a 7-6 (2) 6-2 victory.

"For sure, it wasn't the easiest first round," said the world number one. "She played really well. I tried to find my rhythm, especially in the first set. I'm happy at the end of the set I could win the most important points.

"I'm happy that I am through and I could play a little bit better in the second set."

Remarkably, Swiatek was the only player in her initial section of the draw not to have made an Australian Open final.

Next she will take on another American in Danielle Collins, who ended Swiatek's best run in Melbourne so far by beating her in the semi-finals two years ago before losing to Ashleigh Barty.

That is Collins' only victory in five meetings with Swiatek, who won their most recent match 6-1 6-0 in Cincinnati last summer.

"I can't say that I have an easy draw here," said Swiatek. "I'll try to do my best. Danielle is a really good player. We played really tight matches. On the other hand, our last match, from the score, I had it under control.

"Every match is different. I'm not going to anticipate anything. I'm just going to be ready and we'll see."

Collins was a 6-2 3-6 6-1 winner over former Australian Open, Wimbledon and US Open champion Angelique Kerber.

The German is part of a quartet of mothers making their Melbourne returns along with Caroline Wozniacki, Naomi Osaka and Elina Svitolina having given birth to daughter Liana last February.

"It is for sure different to be back like this," said the 35-year-old. "I think I'm open more than before, and also the other players are. I'm also more relaxed so I feel that they appreciate it and I think it's nice to see so many moms are back on tour.

"It is a long way to be back and to play on a high level again. But, on the other side, I have the experience, I know how it is. I played so many grand slams over the years. So I'm more trying to find my rhythm, to being on court and feeling good again."

There were also victories for two other former grand slam winners, with 18th seed Victoria Azarenka beating Camila Giorgi 6-1 4-6 6-3 and Sloane Stephens seeing off Olivia Gadecki 6-3 6-1.

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