WIMBLEDON, England -- Serena Williams, the reigning Wimbledon champion who seeks her first Olympic singles medal, advanced by beating former No. 1 Caroline Wozniacki of Denmark, 6-0, 6-3. Williams' opponent in the semifinals Friday will be top-seeded Victoria Azarenka of Belarus, who lost when they met in the Wimbledon semifinals last month.
Against the No. 8-seeded Wozniacki, Williams swept the first seven games. As a complement to her booming serve and slingshot returns, Williams kept one point going with a desperation, off-balance left-handed forehand.
"I haven't practiced it in a couple of months," she said. "I wish I could have hit it better."
Williams lost that exchange but won most of the other rallies. She dropped only nine points on her serve, never faced a break point and hit 30 winners to seven for Wozniacki.
"I felt a little off today, believe it or not," Williams said. "But I'm really, really hard to please."
No. 3 Maria Sharapova won a matchup of first-time Olympians, beating Kim Clijsters 6-2, 7-5. Sharapova's opponent Friday will be fellow Russian Maria Kirilenko, who defeated No. 6 Petra Kvitova of Germany 7-6 (3), 6-3.
Azarenka beat No. 7 Angelique Kerber of Germany 6-4, 7-5 under Wimbledon's roof. Kerber eliminated Venus Williams on Wednesday, but Azarenka feasted on the left-hander's serve, winning more than half of those points and breaking six times.
Information from The Associated Press was used in this report.