Top seed and defending champion Iga Swiatek surged closer towards a US Open showdown with Coco Gauff on Friday as 23-time Grand Slam winner Novak Djokovic targeted a place in the last 16.
Swiatek briefly put sentiment to one side as she demolished 145th-ranked Slovenian qualifier and best friend Kaja Juvan 6-0, 6-1 in just 49 minutes to storm into the fourth round.
"I didn't like the fact that I was kind of winning with my best friend," said world number one Swiatek. "It was like playing against a sister because I've known her for so long.
"I don't have many friends but she's my best friend so that was the toughest part for sure."
The Pole is bidding to become the first woman to successfully defend her US Open crown since Serena Williams won a hat-trick of titles from 2012-2014.
She could meet 2017 French Open champion Jelena Ostapenko next ahead of a potential quarter-final clash with in-form home favourite Gauff.
Sixth seed Gauff plays Belgium's Elise Mertens to kick off the evening session on Arthur Ashe.
Czech 10th seed Karolina Muchova qualified for the last 16 courtesy of a 7-6 (7/0), 6-3 win over Taylor Townsend.
She goes on to play China's Wang Xinyu who battled into the fourth round of a Grand Slam for the first time by coming from a set down to oust Slovakia's Anna Karolina Schmiedlova 4-6, 6-3, 6-2.
The 21-year-old from Shenzhen had never been further than the first round at the US Open before this year.
American 14th seed Tommy Paul advanced with a four-set win over Spain's Alejandro Davidovich Fokina, heading into week two of the tournament for the first time as well.
- Djokovic faces fellow Serb -
Djokovic can take another stride towards a record-extending men's 24th Grand Slam crown when he meets Laslo Djere in an-all Serbian match-up in the night session on Arthur Ashe.
"I'm pleased with the way I'm feeling, playing on the court," said Djokovic, who has dropped only 11 games through the first two rounds.
"Can always be better, but first two rounds didn't spend too much time on the court and played very solid and hopefully I can keep building."
Djere, the 32nd seed, is trying to reach the fourth round of a major for the first time in a career marked by the trauma of losing both of his parents to cancer by the time he was 23.
"He had a lot of struggles with his family and private issues. You know, had to endure all of that," Djokovic said. "It says a lot about his mental resilience.
"It's great for Serbian tennis that we have a matchup in the third round. So one Serbian is going to be definitely in the fourth round, which is always great for our tennis."
American No.1 Taylor Fritz later plays teenage Czech qualifier Jakub Mensik, the world number 206 and youngest man to reach the US Open third round since 1990. Mensik celebrated his 18th birthday on Friday.
Former Wimbledon champion Elena Rybakina, who received a walkover in the second round, also faces Romanian veteran Sorana Cirstea under the lights on Louis Armstrong.