The next time Iga Swiatek takes her best friend Kaja Juvan out for dinner, bagels are unlikely to be on the menu.

The world number one and defending US Open champion thrashed Slovakian qualifier Juvan 6-0 6-1 to reach the fourth round at Flushing Meadows.

The pair had been out for a meal in New York last week and Swiatek spoke of their enduring friendship on the WTA Tour before the match.

But with friends like Swiatek, who needs enemies? The Pole surrendered just eight points as she raced away with the first set to love in only 33 minutes.

Juvan did at least avoid the dreaded double bagel, finally getting a game on the board 40 minutes into the match for 3-1 in the second and raising her arms aloft in mock triumph to the acclaim of the Louis Armstrong crowd.

But it was only delaying the inevitable with Swiatek wrapping up another clinical, statement victory – she beat Rebecca Peterson by the same scoreline in the first round – in well under an hour.

“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.”

Caroline Wozniacki’s fairy-tale comeback continued as she came from behind to beat American Jennifer Brady.

The 33-year-old Dane, who retired more than three years ago, won 4-6 6-3 6-1 and is through to the second week in only her third tournament since returning to tennis.

“As a competitor and an athlete you always want to win and you have to believe in yourself, but playing here on Arthur Ashe again is a dream come true,” she said.

“When I retired three years ago and having had two kids, I thought I’d just be here watching. What an honour this is.”

There was further disappointment for the home crowd after Czech 10th seed Karolina Muchova beat another mother, the popular Taylor Townsend, 7-6 (0) 6-3.

But Coco Gauff, seeded sixth, gave them something to cheer after beating Belgium’s Elise Mertens 3-6 6-3 6-0 to set up a clash with Wozniacki.

Swiatek will face Jelena Ostapenko, who found herself gesturing for a rowdy spectator to leave during her win over American Bernarda Pera.

“Yeah, today there was a little bit crazy situation when a fan was shouting during the serves, which he’s not supposed to do,” said the Latvian.

“I was leading 4-1 in the third set, and then suddenly I served a serve and he started to shout like crazy. Not like one or two words, I think two sentences in a row. Of course, the chair umpire told him to be quiet.

“I mean, he just left after the chair umpire told him something, so it was like ‘go, go’.”