Enquirer news services

The announcement that Serena Williams would not defend her U.S. Open title created a wide-open tournament while depriving the field of the most compelling player in women's tennis.

Williams had knee surgery Friday and will be out six to eight weeks, leaving her unable to defend her U.S. Open title later this month in New York.

The world's top-ranked player underwent surgery to repair a partial tear in the mid-portion of the quadriceps tendon of her left knee at an undisclosed location in Los Angeles.

The surgery was done by Dr. Rodney Gabriel on an outpatient basis.

Williams was resting at home in Los Angeles, her spokeswoman said. Her father, Richard, and other family members were with her.

"Serena has suffered from quadriceps tendinitis of her left knee for many years, which has been controlled with medication and physical therapy treatments," Gabriel said.

"She recently developed pain that, although improved with treatment, increased whenever she resumed tennis activities."

The operation puts at least a temporary halt to a remarkable run by Williams, who has won five of the last six Grand Slam titles, all of them in finals against her older sister Venus.

In their most recent Grand Slam meeting, in the Wimbledon final, Serena prevailed 4-6, 6-4, 6-2; Venus was bothered by a strained abdominal muscle.

The WTA Tour said Serena Williams was now certain to lose her No. 1 ranking to Kim Clijsters, who is currently ranked second, or to No. 3 Justine Henin-Hardenne between next week and the first week of September.

Williams, a two-time champion at the U.S. Open, would have been the strong favorite to defend her title, but her absence opens the door for Americans Lindsay Davenport, Jennifer Capriati and Venus Williams, and for Clijsters and Henin-Hardenne, the Belgians who played in the French Open final.

Henin-Hardenne ended Serena Williams' 33-match Grand Slam winning streak in the semifinals at the French Open. The match was controversial for the way the crowd in Paris treated Williams. Down the stretch of her 6-2, 4-6, 7-5 loss, the spectators cheered her errors, then jeered as she left the court.

"There will be no all-Williams final, and I think that's positive," Henin-Hardenne said after that match. "I think people are happy."

The Williams sisters have been battling injuries lately.

Serena pulled out of three tournaments in California before finally having surgery, and Venus recently pulled out of tournaments in San Diego and in Los Angeles.

The U.S. Open begins Aug. 25 at the National Tennis Center in Flushing Meadows-Corona Park in Queens, N.Y.

Gabriel said the events that led to Serena Williams' surgery began Monday, when she had a magnetic resonance imagining test that showed a partial tear in the middle portion of her quadriceps tendon. Surgery was recommended.

Despite their success, or perhaps because of it, the Williams sisters have not won the affection of many tennis fans.

There has been speculation that the results of the sisters' matches were arranged within the family, a suggestion Venus and Serena have always ridiculed.