The former world number one kept her fairytale comeback run in New York going with a 4-6, 6-3, 6-1 win over Jennifer Brady, setting up a potential meeting with the in-form Coco Gauff.

Wozniacki retired after the 2020 Australian Open to start a family, and the mother-of-two is playing just her third event since returning to the tour in Montreal last month.

"Honestly, not really (smiling)," she responded when asked if she was surprised by her level at a tournament where she first reached the fourth round as a teenager in 2008.

"I guess I always had the belief in myself. It takes a little time just to get back into the match rhythm."

"All of that I knew, knowing what I've experienced throughout my career, I knew where I was at. Obviously day by day I feel like I'm getting a little bit better," she continued.

"Would I have been surprised had I lost in the first round? No. Would I be surprised if I keep winning? Also no."

Wozniacki, who was handed a wild card into this year's tournament, trailed Brady by a set and a break but won 12 of the final 14 games.

"If I play my best tennis, I know I'm tough to beat. Someone really has to play well," said the Dane, a US Open finalist in 2009 and 2014.

"At this point I'm just happy to be in the fourth round, and anything can happen from now on, as well."

Wozniacki awaits either home favourite Gauff, the sixth seed, or Belgium's Elise Mertens in the fourth round.

The 33-year-old said last week the chance to return the sport was one she couldn't turn down, but is unsure as to her long-term plans.

"I don't know how long I'm going to play. I get that question all the time. Am I going to play one year? Am I going to play five years? I have no idea," said Wozniacki.

"All I know right now is that I'm really enjoying this moment.

"To be able to play on these big courts in front of a big crowd, it's something very special and something that I will never take for granted, something I'll always appreciate."