MONTREAL (AP) — Canadian teenager Victoria Mboko upset top-seeded Coco Gauff 6-1, 6-4 on Saturday night to reach the National Bank Open quarterfinals.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.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.“Your support was incredible,” Mboko told the crowd in French after a chorus of “Olé, Olé, Olé!” chants echoed around the venue. “I’m really happy to win today. .. It’s incredible. I’m so happy to beat such a great champion.”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.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
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