TORONTO: Second-seeded Serena Williams eased into the quarter-finals of the two million-dollar WTA hardcourt tournament here with a straight sets victory over Ukrainian Alona Bondarenko.

Williams, the reigning Wimbledon, Australian Open and US Open champion, needed only 64 minutes to subdue Bondarenko 6-1, 6-4.

The American exacted a bit of familial revenge after third-seeded Venus Williams was eliminated in the second round by Alona's sister, Kateryna Bondarenko.

"I was just trying to be perfect and I couldn't get my serve in and got frustrated (in the second set)," said Williams. "I've been practicing a lot on my serve. It just hasn't been well."

Kateryna Bondarenko's run came to an end on Thursday at the hands of 14th-seeded Pole Agnieszka Radwanska.

Radwanska was up 7-5, 5-3 and 40-0 when rain stopped play, and when the match resumed she duly finished off a 7-5, 6-3 victory.

In the quarters, she'll face former world number one Maria Sharapova, who shrugged off a rain delay to oust seventh-seeded fellow Russian Vera Zvonareva 6-2, 7-6 (7/3).

"I thought it was a step up, definitely," said Sharapova, who is battling back after a shoulder injury sidelined her for 10 months.

"I had to (play) against somebody that I've had trouble against in the past who I usually play three sets against. It was good to finish the match in two, but I really had no choice. I had to pick it up."

Zvonareva appeared poised to turn the tables when she won four straight games in the second set.

"I think this is definitely a great result," Sharapova said. "I've already played against three great opponents and I'm going to play another opponent tomorrow and you just hope that with each match you can raise your level and play better."

Another comeback kid, Kim Clijsters, was unable to build on an early lead, getting off to a fast start against Jelena Jankovic before the fifth-seeded Serb - winner last week in Cincinnati - steadied to win 1-6, 6-3, 7-5.

In the quarter-finals Jankovic will take on Russian Alisa Kleybanova. Kleybanova toppled giant killer Aravane Rezai 6-3, 6-4, a day after Rezai dispatched world number one Dinara Safina.

Fourth-seed Russian Elena Dementieva, the 2008 Olympic gold medallist, beat Israeli Shahar Peer 6-1, 1-6, 6-4.

In the quarter-finals Dementieva will face Australian Samantha Stosur, a 6-3, 6-1 winner over France's Virginie Razzano.

Czech qualifier Lucie Safarova booked a shot at Williams with a 7-6 (7/3), 6-4 victory over China's Zheng Jie.

While Safina's departure left Williams as the favorite, the American said she couldn't afford to think in those terms.

"I don't really think about it," she said. "I have to get to the final. I have to get there myself."