Serena injures knee, pulls out of semifinal

Williams was down 6-2, 3-1 against Wozniak when she withdrew yesterday, joining sister Venus and Lindsay Davenport on the list of injured home players ahead of the US Open and next month’s Olympics.

“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.”

Williams lasted only 46 minutes before pulling out of the match. She 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.

But Williams had felt healthy most of this year, playing a busy schedule since winning in Miami in the beginning of April. She played 26 matches in a three-month span that went through her loss in the Wimbledon final to Venus.

Then she returned home and played for the Washington Kastles of the World Team Tennis league before arriving at Stanford for her debut in this tournament. Williams wouldn’t blame her decision to play team tennis on her latest setback.