Azarenka, Sharapova, Serena charge into Olympic semis

Australian Open champion Victoria Azarenka, French Open winner Maria Sharapova and Wimbledon titlist Serena Williams posted quarterfinal victories Thursday at the Olympic Games tennis event.

The reigning world No. 1 Azarenka handled seventh-seeded German left-hander Angelique Kerber 6-4, 7-5 on Centre Court at the All England Club, where the Belarusian's semifinal opponent on Friday will be the formidable Williams.

Azarenka needed 1 hour, 46 minutes to get past Kerber in a match that featured 10 service breaks, including six by the winner.

The 23-year-old Azarenka has spent the majority of 2012 at No. 1 after capturing her first major title in Melbourne back in January.

Azarenka will face Williams for a 10th time on Friday, with the American great holding a commanding 8-1 lead in their career head-to-head matchups.

The third-seeded Sharapova, meanwhile, dismissed fellow former world No. 1 Kim Clijsters 6-2, 7-5 in 1 hour, 27 minutes on Centre Court. The Russian superstar is now 4-5 lifetime against the Belgian veteran. Their previous eight matches were all staged on hardcourts.

This marked the 29-year-old Clijsters' last match on Centre Court, as she will retire from tennis for a second time following the upcoming U.S. Open.

Sharapova captured the French Open in June to complete a career Grand Slam and needs an Olympic title to secure a "Golden Slam."

Her semifinal opponent will be compatriot Maria Kirilenko, which guarantees a Russian in the women's gold-medal match. Russia swept the women's singles medals four years ago in Beijing, when Elena Dementieva captured gold, Dinara Safina took home silver, and Vera Zvonareva secured bronze.

The fourth-seeded Williams waltzed past eighth-seeded fellow former No. 1 Caroline Wozniacki of Denmark 6-0, 6-3 on Court 1. Williams whipped Wozniacki in 77 minutes, striking 23 more winners (30-7) and holding her massive serve throughout on Day 6 of this nine-day tournament.

"I felt a little off today, believe it or not," Williams said. "But I'm really, really hard to please."

The mighty Williams, who captured her fifth Wimbledon title in this London suburb just last month, has now won her last 15 matches overall since being shocked by France's Virginie Razzano in the first round at the French Open in May.

The 30-year-old Williams, who is a perfect 11-0 on grass this season, owns 14 major singles titles, but, like Sharapova, needs an Olympic gold medal to complete a "Golden Slam."

A Thursday upset came when a 14th-seeded Kirilenko knocked out sixth-seeded 2011 Wimbledon champ Petra Kvitova of the Czech Republic 7-6 (7-3), 6-3 on Court 2.