The 18-year-old Mboko, ranked 85th in the world, 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 in a round-of-64 match.
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.
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AP tennis: https://apnews.com/hub/tennis