In the women's draw, Sabalenka never looked troubled in a 6-1, 6-4 defeat of Moldova-born Spaniard Cristina Bucsa, ranked 95th in the world.
Sabalenka has now reached the quarterfinals or better at 12 straight Grand Slam tournaments, a consistency she attributes to striking a balance in her life on and off the court.
"I'm super proud, I think that's an incredible achievement," Sabalenka said.
"I think for me the key was balancing on and off-the-court life. I think I've done a great job on balancing really hard work and also great recovery and some fun time outside of tennis court. I think that's been the key."
Sabalenka faces a quarterfinal against either ninth seed Elena Rybakina or the Czech Republic's Marketa Vondrousova, who were playing later Sunday.
Wow 🤩 pic.twitter.com/HhtjEkFYEJ
— US Open Tennis (@usopen) September 1, 2025
In other women's draw action on Sunday, the Czech Republic's unseeded former French Open and Wimbledon champion Barbora Krejcikova conjured a remarkable escape to oust Taylor Townsend, saving an incredible eight match points before digging out a 1-6, 7-6 (15/13), 6-3 victory.
Krejcikova fought off a match point on her own serve at 5-4 down in the second set, and then somehow survived seven match points in an enthralling tie-breaker to move on.
"What a match," said Krejcikova, who revealed she had wondered if she would ever play tennis again after missing the opening months of the season with a back injury.
"I was sidelined for six months and didn't know if I would ever play again. I'm super happy I can be here."
Krejcikova will face American fourth seed Jessica Pegula in the quarterfinals.
Pegula, beaten in the final last year, advanced to the last eight after breezing past compatriot Ann Li 6-1, 6-2 on the Arthur Ashe Stadium court.