An emotional Iga Swiatek survived a major scare to defeat Danielle Collins and reach the third round of the Australian Open.

The world number one lost to Collins in the semi-finals in Melbourne two years ago and it appeared history was about to repeat itself when the American took a 4-1 lead in the deciding set under the roof on Rod Laver Arena.

But Swiatek responded with five games in a row to claim a 6-4 3-6 6-4 victory and set up a clash with Czech teenager Linda Noskova.

The Pole sobbed into her towel at the end of the match, and she said with a relieved smile: “I was at the airport already.

“I wanted to fight until the end. She played perfectly so I knew it would be hard for anybody to maintain that level. I waited for the mistakes to come. I’m really proud of myself because it wasn’t easy.”

Collins walked straight off court into the press room, where she revealed this will be her final season.

“I don’t really know exactly when (I will stop) but this will be my last season and I’m really looking forward to that,” said the 30-year-old, who also made the semi-finals in Melbourne in 2019 and reached a career-high ranking of seven.

“I have other things that I’d like to accomplish in my life outside of tennis, and would like to be able to have the time to be able to do that. Obviously having kids is a big priority for me.”

The semi-final loss was the only one of five previous meetings with Collins that Swiatek had not won, and she lost only one game the last time they faced each other in Cincinnati last summer.

The top seed edged a tight first set disrupted by a brief rain break but the aggression of Collins was troubling the top seed and the American, who also made the semi-finals here in 2019, won five games in a row to take a 5-1 lead in the second set.

She showed nerves, hitting four double faults as she failed to serve it out at the first time of asking, but she was rock solid on her second opportunity.

Swiatek found returns drilled back at her feet and she was staring at the exit door when Collins broke serve twice in succession to lead 4-1 in the deciding set.

However, the American tightened up with the finish line in sight and Swiatek came roaring back, clinching victory on her third match point with a backhand into the corner.

Swiatek applied strapping under her left knee at the start of the third set, but she played down concerns, saying: “I’ve been struggling a little bit with my knee since (the WTA Finals in) Cancun. I have ups and downs but it’s not like it affects my game. You don’t have to be worried.”