The former world No. 1 beat 11th-seeded Petra Kvitová in straight sets, 7-5 7-6, on Wednesday in what was her first victory over a player in the Top-20 in almost five years.
Wozniacki was away from competitive tennis for over three years before returning to action less than a month ago.
The Danish star had two children during her break but always stayed close to the sport, playing legends doubles events and working as a TV analyst.
In June this year, she announced her intention to return and hasn’t looked back since.
She made light work of her first round match at Flushing Meadows and was in brilliant form again against two-time grand slam champion Kvitová.
After the win, an overwhelmed Wozniacki could be seen hunched over in her chair, wiping away tears of joy as the fairytale run in New York continued.
“Obviously, I knew coming into the match that I had a chance to win, and I believe in myself. At the same time, she obviously has had a great year,” Wozniacki said after the match, per the WTA.
“She’s 11 in the world, loves to play on hard courts. I knew it was going to be a very tough one and I had to play my best tennis.”
She later told reporters: “I’m just so thrilled to have an opportunity to play out on Arthur Ashe Stadium. Three years ago, if you’d asked me, I didn’t think I was ever going to play on one of those courts again in the US Open, especially a night session.
“It just feels pretty incredible to be out there and winning a match like that.”
Wozniacki won 30 singles titles, including the 2018 Australian Open, before initially retiring in 2020.
Her last victory over a Top-20 player was against Kvitová again, back in 2018.
The 33-year-old Wozniacki, who was runner-up at the US Open in 2009 and 2014, will now face American Jennifer Brady in the next round.
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