MELBOURNE, Australia - Former World No.1 Caroline Wozniacki kept retirement at bay once more, knocking out No.23 seed Dayana Yastremska, 7-5, 7-5 to reach the third round of the Australian Open.

"I was really nervous going into my first round," an emotional Wozniacki explained during her on-court interview. "Today I actually felt pretty calm, but it quickly became 5-1, and I was thinking, 'Hopefully I can be out here for another 30 minutes to try and take it all in!' After winning this match, which was a really tough one, it's just so special to play in front of such an amazing crowd on one of my favorite courts."

Wozniacki announced her plan to retire at the Happy Slam during the off-season, making each match she plays in Melbourne the last of her career, but the former World No.1 seems as yet unmoored by that pressure as she navigated a tricky match in just over two hours on Margaret Court Arena.

Yastremska came to Melbourne as one to watch following her runner-up finish at the Adelaide International, where she fell to World No.1 Ashleigh Barty. The Ukrainian teenager, who began working with coach Sascha Bajin last fall, made her Grand Slam breakthrough at this event last year, reaching the third round, where she faced childhood idol and 23-time Grand Slam champion Serena Williams.

With a win over Wozniacki at last year's Western & Southern Open, Yastremska seemed poised to send the Dane into retirement as she raced ahead 5-1 with some authoritative hitting. Wozniacki, who captured her maiden major title Down Under back in 2018 - with a thrilling win over fellow former World No.1 Simona Halep in the final - wouldn't be set aside so easily and promptly went on a tear.

"She came out really flying, hitting so hard and so precise. I just didn't know what to do. She started making a few more errors, and I started to get a little more depth on the ball and tried to mix up the pace. The crowd also really got behind me, so that was so special!"

In the next four games, Wozniacki lost just two points as she swiftly leveled the set, and dug out of a titanic 11th game to edge ahead and ultimately break Yastremska to win a sixth game in a row - and the set - with the clean game style that kept her at the upper echelon of the sport for over a decade, striking eight winners to five unforced errors.

"There was no real proper feeling out there today because she came out swinging, and she started making the lines and everything was going in, even balls that I don't think she knew were possible to hit it that way.

"I was just thinking to myself, 'It surely can't continue. If it's going to continue, then there is not much I can do out there.'

"I also knew if I could stay with her the first two, three points after the serve and after the return, then it was getting more into my favor. So that's really what I was going to try and do out there."

Yastremska shook off the shock early in the second set and took another big lead, breaking Wozniacki twice more to move ahead 3-0. Wozniacki clawed level once more, taking back one break, then the other as the score soon stood at four games apiece.

The No.23 seed mounted a brave last stand, saving five match points over two games on her serve - saving the fifth after a 17-shot rally - but couldn't save a sixth, and it was Wozniacki who secured victory when Yastremska put one last forehand long.

"I was just trying to stay focused," she said after the match. "I had match point. I had chances. I didn't take them. Some of them she played well; some of them I played too passively.

"In the end I just tried to keep focusing, just keep grinding, keep hanging in there. And I finally made it at 6-5 for me, and that was a nice relief."

In all, she struck an even 15 winners to 15 unforced errors, and while Yastremska made almost double the amount of winners, she also made nearly 50 unforced errors, finishing the match with a -11 differential (36 to 47). Wozniacki maintained an impressively high first serve percentage in the face of Yastremska's aggressive returns at 72%, winning 62% of those points while breaking serve six times throughout the match.

In the same section of the draw as Williams - her good friend and ASB Classic doubles partner, with whom she reached the final - Wozniacki will next face Ons Jabeur, who scored the first upset of the fortnight when she ousted No.12 seed and former Australian Open semifinalist Johanna Konta in straight sets.

2020 Australian Open press conference: Wozniacki ‘The crowd is really supporting me’