Injured Serena quits WTA showpiece

MADRID, Spain -- Former world number one Serena Williams has withdrawn from the WTA Championships in Madrid after injuring her left knee in her opening match against Russia's Anna Chakvetadze on Wednesday night.

The American's place in the WTA's end of season showpiece tournament will go to Marion Bartoli of France.

Wimbledon runner-up Bartoli faces a daunting opening match later on Thursday against top seed Justine Henin who suffered a shock semifinal defeat to the Frenchwoman at the All England club.

Australian Open champion Williams had to abandon after dropping the first set 6-4 and a knee scan later confirmed that she would be ruled out of the tournament that brings together the leading eight players in the WTA rankings.

"I felt it maybe a little bit yesterday, but it wasn't too intense," Williams said. "I had a really short practice yesterday, and the day before I had a short practice. It's really unfortunate."

Bartoli, who will be making her debut in the WTA Championships, was the last player to defeat Belgium's Henin with her Wimbledon upset win.

Following that, Henin is unbeaten in 22 games during which she won the U.S. Open title in September.

The last of those victories saw the defending champion through to the semifinals in Madrid, having beaten Jelena Jankovic of Serbia 6-2 6-2 on Wednesday night.

In other action on Wednesday night, Ana Ivanovic of Serbia moved closer to the final four by knocking out Slovakia's Daniela Hantuchova with a 6-2 7-6 win in red group play. E-mail to a friend