Petra Kvitova dominated Kristina Mladenovic to reach the last eight in Cincinnati, but No. 3 seed Sloane Stephens offered a sloppy display and fell in straight sets to Elise Mertens.
Stephens twice served for the first set and had several set points in the subsequent tiebreak, but failed to convert her opportunities — as Mertens did — and the Belgian notched a 7-6, 6-2 victory. It was a poor output from the US Open champion, who played exceptionally well in reaching the Montreal final a week ago but won just one match in the American midwest.
Stephens played exceptional defense throughout the first set, but paired it with errors on her service games. After three missed set points, Mertens knocked a looping backhand into the corner on a set point of her own, putting her firm firmly in front.
She added to it in the second set, breaking to go up 3-2, and saved two break points in the subsequent game. Stephens unraveled from there, going down a second break at love with two loose, long groundstrokes. The No. 15 seed, a semifinalist in San Jose and quarterfinalist in Montreal, closed out a final game with several more Stephens errors.
Kvitova, meanwhile, had a far easier victory than her three-set classic against Serena Williams on Tuesday. She needed barely an hour and a half to dispatch Mladenovic, earning 18 break points and displaying her trademark power from both sides of the court. The Frenchwoman, for her part, won just 28 percent of her many second serve points.
She raced to a 5-0 lead in the second set — a frame in which she forced 11 break points — then secured the match two games later with a powerful forehand on the run. The two-time Wimbledon champion escapes an uphill clash against Stephens, but still faces a test against Mertens.
No. 6 seed Caroline Garcia, meanwhile, blew a match point in the third set, allowing Aryna Sabalenka to come back and win 6-4, 3-6, 7-5 in more than two and a half hours. Garcia had break point on 14 occasions and won Sabalenka’s first two final set service games, but could not close out the victory.
The Belarussian faces Madison Keys, a three-set victor over Angelique Kerber, on Friday.
