Gauff dropped to 2-3 since winning the French Open. She followed the major victory with opening losses in Berlin and Wimbledon, then overcame double-fault problems to win two three-set matches in Montreal. Gauff had five double-faults Saturday after having 23 in her opener against Danielle Collins and 14 against Veronika Kudermetova.
“She’s playing high-level tennis.” Gauff said. “I think that’s what showed today. I think she was the better player.”
The 18-year-old Mboko, ranked 85th in the world, finished off the 21-year-old Gauff — who had 24 unforced errors — in 1 hour, 22 minutes. Mboko will face the winner of the late match between Lin Zhu of China and Jessica Bouzas Maneiro of Spain.
In Rome in May, Gauff rallied to beat Mboko 3-6, 6-2, 6-1.
“I was actually really thinking about it a lot during the match,” Mboko said. “I had flashbacks to when I played her in Rome a little bit. I just remember when she came out playing even better and stepped it up a bit better. Wanted to step my game up a little bit more and make sure I matched whatever she was producing, and I wanted to stay right there with her.”
Earlier, 24th-seeded Marta Kostyuk of Ukraine and ninth-seeded Elena Rybakina of Kazakhstan set up a quarterfinal match. Kostyuk beat McCartney Kessler of the United States 5-7, 6-3, 6-3, and Rybakina topped Dayana Yastremska of Ukraine 5-7, 6-2, 7-5.
___
AP tennis: https://apnews.com/hub/tennis