BEIJING -- Coco Gauff advanced to the quarterfinals of the China Open when Naomi Osaka retired at 3-6, 6-4 because of a lower back injury.
Osaka, a four-time major champion, was leading 4-3 in the second set before Gauff won three straight games.
The sixth-ranked Gauff then helped carry Osaka's bags off the court.
Gauff hit six aces compared to Osaka's one and improved to 3-2 over her opponent at WTA tournaments.
She will next meet No. 115-ranked Yuliia Starodubtseva, who earlier upset No. 14 Anna Kalinskaya 7-5, 6-0.
Paula Badosa reeled off 11 of the last 12 games in a 6-4, 6-0 victory over US Open finalist Jessica Pegula to reach her eighth career quarterfinal at a WTA 1000-level event.
"She's one the of the players I never want to face -- she's very solid, hits very flat, changes very well direction," said Badosa, who was 0-3 previously against Pegula. "I prepared myself for a battle, but I think today everything worked pretty well."
Badosa next faces 35-year-old Chinese player Zhang Shuai, who continued her resurgence with a 6-4, 6-2 win over Magdalena Frech of Poland.
Zhang entered the China Open on a 24-match losing streak and ranked No. 595, but she's yet to drop a set in four matches this week.
Zhang is now into her first women's tour quarterfinal since Tokyo in 2022, and her first at a WTA 1000 tournament since Cincinnati in the same year.
"In this draw, everyone has a higher ranking than me," Zhang said. "Just step on court, just play. So I do not have much to think about, to prepare. I will just focus on myself."