Aryna Sabalenka reached the US Open quarter-finals for the fourth year in a row with an assured victory over Elise Mertens.
Second seed Sabalenka, beaten by Coco Gauff in the New York final last year, saw off her former doubles partner Mertens 6-2 6-4.
The Belarusian hit 41 winners and saved all eight of the break points that Belgium's Mertens created.
Sabalenka is the first woman to reach four consecutive women's singles quarter-finals at Flushing Meadows since Serena Williams in 2016.
She has now made the quarter-finals or better in her past eight Grand Slam appearances.
Her last defeat before that stage came at the 2022 Australian Open, where she was beaten by Kaia Kanepi in the fourth round. She has not lost a match in Melbourne since, winning the title in 2023 and defending it in January this year.
Sabalenka will face China's Olympic champion Zheng Qinwen, who beat silver medallist Donna Vekic 7-6 (7-2) 4-6 6-2, in the last eight.
A match which lasted two hours 50 minutes ended at 2.15am local time on Monday, the latest finish to a women's US Open match.
Sabalenka beat Zheng in the Australian Open final this year.
Paula Badosa earlier breezed past Wang Yafan 6-1 6-2 to set up a quarter-final against Emma Navarro, who ended Gauff's title defence in a three-set win.
She has now made the quarter-finals or better in her past eight Grand Slam appearances.
Her last defeat before that stage came at the 2022 Australian Open, where she was beaten by Kaia Kanepi in the fourth round. She has not lost a match in Melbourne since, winning the title in 2023 and defending it in January this year.
Sabalenka will face China's Olympic champion Zheng Qinwen, who beat silver medallist Donna Vekic 7-6 (7-2) 4-6 6-2, in the last eight.
A match which lasted two hours 50 minutes ended at 2.15am local time on Monday, the latest finish to a women's US Open match.
Sabalenka beat Zheng in the Australian Open final this year.
Paula Badosa earlier breezed past Wang Yafan 6-1 6-2 to set up a quarter-final against Emma Navarro, who ended Gauff's title defence in a three-set win.
Paula Badosa was born in New York before moving to Barcelona aged seven
Former world number two Badosa is into a second Grand Slam quarter-final after a difficult few years.
Badosa first broke through in 2021, winning the Indian Wells title before a run to the last eight of that year's French Open.
However, a stress fracture in her back ruled her out of the second half of the 2023 season and has troubled her since.
She has not won a title since January 2022 and considered retirement after struggling with the impact of the injury.
"A few months ago, I was thinking to quit this sport because I stopped believing in myself and my injury wasn't responding," Badosa said.
"The low point for me was at the middle of the season. There were moments that I didn't know what to do.
"In my mind I was thinking, maybe I should quit because if I'm not in the highest level, I don't want to play this sport.
"So to be back is a dream come true."
In the women's doubles, Britain's Heather Watson and American partner Asia Muhammad lost their third-round match against Katerina Siniakova and Taylor Townsend 6-1 5-7 7-5.