Caroline Wozniacki has won the battle of US Open comeback queens by rallying to beat Jennifer Brady 4-6 6-3 6-1 and move into the last 16 of the season's final grand slam.

Wozniacki and Brady have been the feel-good stories at Flushing Meadows and their storylines converged on a sun-kissed Arthur Ashe Stadium court on Friday with the 33-year-old Dane continuing her dazzling return by reaching the fourth round.

It seemed improbable just weeks ago ex-world No.1 Wozniacki, back playing competitive tennis after a three-year break to raise a family, and Brady, rising star and Australian Open finalist in 2021 but sidelined for two years with knee and foot injuries, would face each other at a major.

But 28-year-old Brady, just four tournaments into her comeback, and Wozniacki, playing in her third, looked as if they had never been away by treating fans to some quality tennis that at times had the crowd on their feet.

However it was the twice a US Open finalist, who showed more fitness and a little less competitive rust and will now prepare to face sixth seed Coco Gauff, who beat Belgian Elise Mertens 3-6 6-3 6-0.

The American teenager set aside a rough start to grab the last 10 games for the win over the No.32 seed.

"When she retired I remember saying that I wish I could have played her. So that wish came true so I'm really excited," Gauff said of her upcoming challenge with Wozniacki.

"She's still fit and going strong. I think it's going to be an exciting match.

Big-hitting fourth seed Elena Rybakina is out though, beaten for the first time in her career by Romanian Sorana Cirstea, 6-3 6-7 (6-8) 6-4.

Cirstea broke the former Wimbledon champion in the fourth game of the opening set, and the seasoned world No.30 continued to dictate points from the centre of the court.

She will face Belinda Bencic in round four after the Swiss recorded a 7-6 (7-1) 2-6 6-3 victory against Lin Zhu of China.

Earlier, world No.1 and defending US Open champion Iga Swiatek thrashed Slovakian qualifier Kaja Juvan 6-0 6-1 in just 49 minutes to advance.

"I didn't like that I was winning with my best friend but I knew I had to be focused and not think about that," said the 22-year-old.

"It's like playing your sister. I don't have many friends and she's my best friend so that was the toughest, for sure."

Karolina Muchova also moved on with a 7-6 (7-0) 6-3 victory over Taylor Townsend.

Muchova, the 10th-seeded Czech who reached the final of this year's French Open, equalled her best showing in New York by pushing the serve-and-volleying American off the net and onto the baseline.

Muchova next faces China's Xinyu Wang, a 4-6 6-3 6-2 winner over Anna Karolina Schmiedlova of Slovakia.

With Reuters.