Williams, who hurt her left thumb and calf at Wimbledon after being picked for the U.S. squad, was replaced by Meilen Tu.

"I've talked to (Serena) and I've also gotten an e-mail. She wasn't very happy that she wasn't able to come," U.S. captain Zina Garrison said. "The doctors advised her, for this week, it wouldn't be a good idea to risk possibly straining her thumb a little bit more."

The No. 4-ranked Kuznetsova's spot went to Alla Kudryavtseva, a teenager who was two points away from beating Venus Williams in the first round at Wimbledon _ before the American pulled out a three-set victory and went on to win her fourth All England Club title.

Anna Chakvetadze, Nadia Petrova and Elena Vesnina make up the rest of the Russian team. Second-ranked Maria Sharapova withdrew Tuesday with a right shoulder injury.

Tu joins Venus Williams, doubles specialist Lisa Raymond and Vania King on the U.S. team.

"I was so excited to get the phone call. It's my first time being on the Fed Cup," the 41st-ranked Tu said. "I have a great team, a great coach, great captain. It's just unbelievable."

The draw for the best-of-five semifinal is Friday, with matches Saturday and Sunday.

"The only thing we knew when we came into this _ it was going to be a tough match no matter who was here, whether Serena was here or not," Garrison said. "We're still going to go out and play as well as we can play."

The matches will be played on hard courts, which Vesnina thinks will work well for the Russians.

"It's a good surface for us," she said. "It was a little bit difficult on the first day when we were playing, because, maybe, we were up in the mountains _ that's why the ball (was) flying really fast for us. But I think after a few days, we'll get used to that."