WASHINGTON (AP) -- Third-seeded Sloane Stephens of the United States survived a three-set opening match against Bulgaria's Sesil Karatantcheva 6-3, 2-6, 6-1 in the first round of the Citi Open on Monday.
Second-seeded Chanelle Scheepers of South Africa and fifth-seeded Barbora Zahlavova Strycova of the Czech Republic were not so lucky.
American Brian Baker, a shock participant in the round of 16 at Wimbledon earlier this year, dropped the final two sets to Frenchman Florent Serra and was eliminated, 4-6, 6-3, 6-4 in the men's tournament.
Scheepers, ranked No. 42 in the world, fell 6-2, 6-1 to Magdalena Rybarikova of Slovakia. Zahlavova Strycova was beaten by Romania's Edina Gallovits-Hall, 7-5, 4-6, 6-3.
After losing the final three games of the second set, including two on her own serve, Stephens opened the third by breaking Karatantcheva twice for a 3-0 lead. The 19-year-old American, who reached the fourth round at the French Open and the third round at Wimbledon this year, tacked on two more breaks of serve to advance.
No. 7 seed Coco Vandeweghe of the United States avoided an upset by defeating Erika Sema of Japan 6-4, 6-1. Eighth-seeded Olga Govortsova topped Karolina Pliskova 6-2, 6-2, and Leonardo Mayer beat Guillermo Garcia-Lopez 7-6 (5), 7-6 (8) to advance to the second round.
The Washington tournament, a staple on the ATP schedule, is combining with the WTA Tour for the first time.
Mardy Fish, the top-seeded men's player, is scheduled to play his opening match on Tuesday.
Fish, the No. 13 ranked player, skipped the Olympics after missing several weeks on tour earlier this year following a procedure to correct a heart problem.
Russian Anastasia Pavlyuchenkova is the top seed in the women's draw.