The New Nation - Internet Edition

AFP, California

Serena Williams's march toward a fourth WTA title of 2008 came to a premature halt Saturday, as an injured knee and Canadian qualifier Aleksandra Wozniak proved too much for the top seed.

Williams retired with a left knee injury while trailing Wozniak 2-6, 1-3 at the 600,000- dollar hardcourt event in Stanford.

Williams, ranked fifth in the world, has come up empty in Grand Slams this year, including falling to elder sister Venus in the Wimbledon final. But she has had plenty of WTA success with three titles this year.

Wozniak, currently ranked 85th in the world, showed no sign that she was intimidated by the 26-year-old American.

After Williams won the opening game, Wozniak captured the next three and quickly closed out the opening set as her opponent started limping.

Williams had her left knee wrapped, but still was laboring early in the second set and retired 47 minutes after the match had begun.

Wozniak, 20, won 70 percent of her service points and capitalized on three of four break chances to advance to just her second WTA final.

"I tried to stay focused on me," Wozniak said. "I knew I would play a big champion.

"I just wanted to play really aggressive, to take the ball as early as I could and come in when I could.

"In the middle of the first set, I saw her watching a little bit her leg," Wozniak added. "I thought it was her ankle, but in the end it was the knee."

Wozniak will be attempting to capture her first singles title on Sunday, when she takes on the winner of the second semi-final between sixth-seeded Frenchwoman Marion Bartoli and unseeded Japanese veteran Ai Sugiyama.

Bartoli took a huge step toward getting her season revved up on Friday, when she upset second seed and defending champion Anna Chakvetadze of Russia in the quarters.

The 23-year-old Bartoli, a surprise finalist at Wimbledon last year, is just 15-16 this season and has yet to appear in a final.

For that to change, Bartoli will have to reverse her fortunes against Sugiyama, who has won all five of their previous meetings.

Sugiyama, 33, is attempting to reach her second final at this event. She was runner- up in 1995, when the tournament was held in Oakland.

Sugiyama hasn't played in a final in two years, and won her last title four years ago.