American Jessica Pegula, the No. 6 seed, reached the second week of the US Open without dropping a set, overwhelming Spain's Jessica Bouzas Maneiro 6-3, 6-3 in their first meeting Saturday.

Bouzas Maneiro grabbed attention at Wimbledon by eliminating defending champion Marketa Vondrousova in the first round.

"I thought I just played solid," Pegula said in her on-court interview. "I didn't do anything crazy ... bad or amazing."

Against Pegula, Bouzas Maneiro had 29 unforced errors and only five winners.

Since the start of 2021, Pegula has won 25 matches at the hard-court Slams, trailing only Aryna Sabalenka and Iga Swiatek. She next faces No. 18 seed Diana Shnaider, who earned a straight-sets win over Italy's Sara Errani.

Earlier Saturday, Jasmine Paolini defeated No. 30 seed Yulia Putintseva 6-3, 6-4 en route to the round of 16, becoming the first Italian woman to reach that stage of the New York major since Roberta Vinci in 2016.

The fifth-seeded Paolini, 28, joined Coco Gauff as the only women to reach at least the fourth round at every Grand Slam tournament in 2024.

Paolini had never made it past the second round in 16 appearances at majors entering this season. But she reached the fourth round at the Australian Open in January before being the runner-up at both the French Open in June and Wimbledon in July.

Since the Open era began in 1968, only two other women have made their first four major round of 16 appearances in the same year: Christina Sandberg (1970) and Eugenie Bouchard (2014).

Paolini, whose 18 match wins at Slams rank first among women this season, compiled 13 of her 22 winners off the forehand side against Putintseva at Louis Armstrong Stadium and will meet 2023 French Open finalist Karolina Muchova on Monday for a berth in the quarterfinals at Flushing Meadows.

Muchova is back in the fourth round at a Grand Slam tournament for the first time since having surgery on her right wrist, doing so by beating Anastasia Potapova 6-4, 6-2.

Muchova made it to the semifinals at Flushing Meadows in 2023 before losing to Gauff. But Muchova didn't play again last season and had a wrist operation in October, returning to the tour in June.

"I'm trying every day to put some work in and get back to where I was -- maybe even better," Muchova said.

She defeated four-time Slam champion and former No. 1 Naomi Osaka on Thursday and has won all three of her matches this week in straight sets.

"To save some energy is always nice. ... Couldn't be better so far," said Muchova, who has been ranked as high as No. 8 and is currently No. 52. "Last year was amazing. I'm trying to follow up."

Against the 38th-ranked Potapova on Grandstand, Muchova displayed the same varied game that worked so well against Osaka.

There were eight aces, 24 winners and just 11 unforced errors. She saved both break points she faced.

ESPN Stats & Information and The Associated Press contributed to this report.