MASON, OHIO - Former world No. 1 and 2010 runner-up Maria Sharapova and former champion Vera Zvonareva were a pair of quarterfinal winners Friday at the $2.05 million Western & Southern Open, a U.S. Open Series event.

The fourth-seeded Sharapova pasted last week's Toronto runner-up Samantha Stosur 6-3, 6-2 in 72 minutes on the hardcourts at the Lindner Family Tennis Center. The world No. 7 Sharapova won a challenge on match point Friday to improve to 9-0 lifetime against Stosur, including a 3-0 record this season.

"I didn't give her much time to do the things she likes to do," Sharapova said after the win.

The 10th-seeded 2010 French Open runner-up Stosur lost to American great Serena Williams in last week's title tilt at Canada's Rogers Cup event.

The three-time major champion Sharapova was last year's Cincy runner-up to U.S. Open champ Kim Clijsters and this year's Wimbledon runner-up to Czech left-hander Petra Kvitova.

The second-seeded Zvonareva, meanwhile, got past former top-10 Slovakian Daniela Hantuchova 6-3, 7-6 (8-6) to set up a semifinal showdown with her fellow Russian Sharapova, who has won six of their nine career meetings.

The 2010 U.S. Open runner-up Zvonareva titled here in 2006 and was the Cincinnati runner-up in 2004.

Meanwhile, ninth-seeded rising German Andrea Petkovic popped six aces and reached the final four here with a 7-5, 6-1 victory over former top-10 Russian Nadia Petrova, the 2009 Western & Southern titlist.

Serbian Jelena Jankovic advanced to the semis with a walkover of China's Peng Shuai, who withdrew from the match with a left hip injury.

The former world No. 1 Jankovic captured this Cincy event two years ago.

The 2011 Cincinnati champion will collect $360,000.