Ukraine’s Lesia Tsurenko stunned defending Cincinnati Masters champion Garbine Muguruza as the world’s top players faced difficulty during a rain-shortened second round on Wednesday.
Tsurenko took down the seventh-seeded Spaniard 2-6 6-4 6-4 in the early match, which was a preview of the challenges faced by top seeds during the day.
World number one Simona Halep fell down a set but rallied against Australia’s Ajla Tomljanovic, and was leading 4-6 6-3 4-3 when her match was suspended due to rain.
Second seed and Australian Open champion Caroline Wozniacki lasted just one set against Kiki Bertens before retiring due to a left knee injury.
“It’s never nice to win when someone has to retire,” Bertens said. “I felt she was struggling a bit with her serve. She seemed to struggle with her movement as well.”
Fourth seed Angelique Kerber also had a difficult outing, having to battle back to outlast Anastasia Pavlyuchenkova 4-6 7-5 6-4.
Muguruza was competing in her first tune-up event for the Aug. 27-Sept. 9 U.S. Open, having been sidelined due to an arm injury that forced her to withdraw from a pair of tournaments.
It was her first match since losing in the second round at Wimbledon.
“I’m happy that I didn’t feel pain,” she said. “I competed. It didn’t go my way. I’m going to take that positive and keep training for US Open.”
Next up for Tsurenko is a clash with Ekaterina Makarova after the Russian topped Frenchwoman Alize Cornet 6-2 6-0.
Joining Tsurenko in the third round was U.S. Open champion Sloane Stephens, who enjoyed a routine 6-3 6-2 win over German Tatjana Maria.
Stephens, who finished runner-up to Halep in Montreal on Sunday, continued her fine form on the North American hard courts and controlled the tempo throughout her 71-minute match.
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.
Also advancing to the third round was Belarusian Aryna Sabalenka, who upset Czech ninth seed Karolina Pliskova 2-6 6-3 7-5, and Australian Ashleigh Barty, a 7-5 6-3 winner over Estonia’s Kaia Kanepi.
American Amanda Anisimova had a 5-4 lead on Croatia’s Petra Martic in a match that was also halted because of rain.