Garbine Muguruza lost to Lesia Tsurenko in three sets, 2-6 6-4 6-4, as defending champion in the Cincinnati Open, which means that next week she will leave the top 10.
Muguruza was competing in her first tune-up event for the August 27-Sept. "I felt good. I'm happy that I didn't feel pain", Muguruza said.
Second seed Caroline Wozniacki, however, retired with a left knee injury after surrendering the first set 6-4 to Kiki Bertens.
It was Muguruza's first match since her defeat in the second round of Wimbledon, where she was also defending her title.More news: Chopras to host Priyanka, Nicks engagement bash
The Wimbledon champion called for the doctor during the second set but put aside his discomfort to progress 4-6, 6-2, 6-1 over the Frenchman before rain halted afternoon play for almost three hours. Just experience to work hard and to never lose the, how you say, motivation to believe you can do it'. "She seemed to struggle with her movement as well".
Germany's Angelique Kerber, the reigning Wimbledon champion, is also through after she beat Russia's Anastasia Pavlyuchenkova 4-6, 7-5, 6-4.
After withdrawing from San Jose and Montreal due to an arm injury, Muguruza got off to a nervy start, saving two break points in the opening game and failing to convert her own chances in the second.
Aug 15, 2018; Mason, OH, USA; Garbine Muguruza (ESP) is unable to return a shot against Lesia Tsurenko (UKR) in the Western and Southern Tennis Open at Lindner Family Tennis Center. I competed. It didn't go my way.More news: Tom Brady, Nick Foles finally connect after missed Super Bowl handshake
"I'm happy that I didn't feel pain", she said.
Tsurenko will next play Ekaterina Makarova after the Russian dismantled Alize Cornet 6-2 6-0.
Stephens will next face Elise Mertens after the 15th-seeded Belgian earned a 3-6 6-2 7-6 (1) win over Swedish qualifier Rebecca Peterson.More news: Trump administration creates Iran Action Group at State Department
Other second-round winners included 16th seed Ashleigh Barty and American Madison Keys.