Aug. 27 (UPI) -- Fifteen-year-old American star Cori "Coco" Gauff earned a comeback win over Russian Anastasia Potapova on Tuesday at the USTA Billie Jean King National Tennis Center in Flushing, N.Y., to reach the second round of the 2019 U.S. Open.
Gauff dropped the first set but rallied to defeat the fellow junior Grand Slam champion 3-6, 6-2, 6-4. Gauff will take on Hungarian qualifier Timea Babos in the next round.
In other matches from the women's draw, defending U.S. Open champion Naomi Osaka shook off a nervous start to defeat 20-year-old Russian Anna Blinkova 6-4, 6-7 (5), 6-2 in their first-round match.
The top-seeded Osaka, who admitted to being nervous in the early stages of the match, fell into a 4-1 hole in the opening set before winning five straight games to take the lead.
After losing a tiebreaker in the second set, Osaka fought off three more break points early in the final set and went on to claim the victory. The world No. 1 had 50 unforced errors. Blinkova had only 22.
Wimbledon champion Simona Halep was challenged by American Nicole Gibbs in the first round. The fourth-seeded Halep was taken to a third set but claimed a 6-3, 3-6, 6-2 victory.
Seventh-seeded Kiki Bertens defeated Paula Badosa in straight sets, and No. 6 seed Petra Kvitova beat Denisa Allertova 6-2, 6-4 to reach the next round.
In the men's draw, No. 4 seed Dominic Thiem and eighth-seeded Stefanos Tsitsipas each suffered upset losses.
Unseeded Thomas Fabbiano defeated Thiem 6-4, 3-6, 6-3, 6-2, while unseeded Russian Andrey Rublev edged Tsitsipas 6-4, 6-7 (5), 7-6 (7), 7-5.
No. 6 seed Alexander Zverev beat Radu Albot 6-1, 6-3, 3-6, 4-6, 6-2. 14th-seeded John Isner dominated Guillermo Garcia-Lopez in straight sets.