Reigning French and U.S. Open champion Serena Williams and former world No. 1 Victoria Azarenka were easy third-round winners Thursday at the $2.37 million Western & Southern Open, a hardcourt U.S. Open tune-up.
Williams, this week's top-seed and last week's big winner in Toronto, needed just over an hour to dispose of German Mona Barthel, notching a 6-4, 6-1 triumph to set up a quarterfinal matchup with Romanian Simona Halep.
Halep punched her ticket to the round of eight by knocking off 11th-seeded Samantha Stosur by a 6-4, 4-6, 6-2 margin.
The second-seeded Belarusian star Azarenka handled Slovak and recent Washington, D.C. titlist Magdalena Rybarikova, 6-3, 6-4, at the Lindner Family Tennis Center.
Azarenka, the reigning Australian Open champion and U.S. Open runner-up, will take on 10th-seeded Caroline Wozniacki of Denmark in the quarterfinals after Wozniacki upended seventh-seeded Czech Petra Kvitova, 3-6, 6-2, 6-3.
Meanwhile, fourth-seeded former Wimbledon runner-up Agnieszka Radwanska pummeled Russian Elena Vesnina 6-0, 6-2, and in a rematch of last year's Cincinnati final, fifth-seeded and defending champ Li Na beat ninth-seeded German Angelique Kerber, once again, this time by a 6-4, 6-4 margin.
Poland's Radwanska and China's Li were set to square off in the round of eight, but Radwanska revealed after her quarterfinal victory that she is withdrawing from her match with Li to attend her grandfather's funeral.
A Day-4 upset came when 12th-seeded Roberta Vinci toppled her good friend and doubles partner Sara Errani, this week's sixth seed, by a 6-4, 6-3 score. Vinci is now 2-1 versus her higher-ranked compatriot this year and 4-5 lifetime. Vinci upset Errani in a final in Palermo in their native Italy just last month.
Former top-ranked Serb Jelena Jankovic, seeded 14th, cut down American Sloane Stephens, 3-6, 7-5, 7-5. The 2009 Cincy champ and 2011 runner-up Jankovic will face Vinci on Friday.
This week's champion will earn $426,000. The tournament is part of the U.S. Open Series, or the North American hardcourt events that lead up to the U.S. Open, which will commence August 26.