Serena Williams' busy summer schedule caught up with her, making her the latest U.S. Olympian dealing with a knee injury as the Beijing Games approach.

Williams injured her left knee and pulled out of the Bank of the West Classic on Saturday at Stanford, Calif., becoming the third singles player on the U.S. women's tennis team with a knee injury.

Williams retired from her match after losing the first set and falling behind in the second set of her semifinal against qualifier Aleksandra Wozniak.

"It was hurting in practice, and I didn't really practice too long because it was hurting," Williams said. "After I got off, it was really swollen. I thought that I have to play really fast."

She lasted only 46 minutes before pulling out of the match trailing 2-6, 1-3. Williams said the injury is different than one that forced her to undergo surgery on her left knee in 2003 and miss eight months. But that knee has bothered her since, forcing her to drop out of the 2004 Athens Olympics and to miss significant time again in 2006.

Venus Williams and Lindsay Davenport, the other U.S. Olympic singles players, have already pulled out of next week's East West Bank Classic in Carson, Calif., due to right knee injuries. Serena Williams said she still plans to go to Carson but will likely have an MRI exam before then and could choose to rest up for the Olympics next month.

"I do plan on obviously being at the Olympics," she said. "That's my main goal."

INDIANAPOLIS TENNIS CHAMPIONSHIPS: Top-seeded James Blake struggled after a rain delay and was upset by defending champion Dimitry Tursunov 4-6, 6-3, 6-4 Saturday in the semifinals at Indianapolis.

Tursunov, the third seed, will meet second-seeded Gilles Simon of France in the championship match today. Simon outlasted fourth-seeded American Sam Querrey 6-3, 4-6, 6-4 in Saturday's other semifinal.

CROATIA OPEN: Top-seeded Fernando Verdasco needed less than an hour to beat Fabio Fognini of Italy 6-1, 6-3 Saturday in the semifinals at Umag, Croatia.

In the final, Verdasco will face fourth-seeded Igor Andreev of Russia, who beat Maximo Gonzalez.

DUTCH OPEN: Defending champion Steve Darcis reached his third career ATP Tour final Saturday by beating top-seeded Frenchman Marc Gicquel 7-6 (3) 3-6 7-5 at Amersfoort, Netherlands.

He will play fifth-seeded Spaniard Albert Montanes, who beat countryman Oscar Hernandez 6-1, 6-3 in the other semifinal.

AUSTRIAN OPEN: Jurgen Melzer will play Juan Martin del Potro in the final at Kitzbuehel, Austria.

Melzer beat last year's runner-up Potito Starace 6-4, 6-7 (8), 6-3 on Saturday to reach his first final of the year, and Del Potro defeated Victor Hanescu 6-3, 7-6 (5).

GASTEIN LADIES TOURNAMENT: Pauline Parmentier of France will play qualifier Lucie Hradecka at Bad Gastein, Austria.

The fourth-seeded Parmentier upset top-seeded Agnes Szavay 6-4, 6-2 in Saturday's semifinal, while 237th-ranked Hradecka defeated Mariya Koryttseva of Ukraine 6-3, 6-2.

MURRAY GETS OLYMPIC BERTH: Ninth-ranked Andy Murray will represent Britain in singles tennis at next month's Olympic Games, his first, and partner brother Jamie in the doubles. The Scots' inclusion was announced Saturday by the British Olympic Association.