Andre Agassi strained his back when his car was rear-ended in Las Vegas, forcing him to miss the U.S. team's Davis Cup semifinal next week.

Agassi's car was hit as he rode to his Las Vegas home from the airport after returning from Wimbledon on Sunday, the U.S. Tennis Association said.

Agassi has muscle spasms in his right side and can't raise his right arm above his shoulder.

``It's a big loss for me and the team,'' U.S. Davis Cup captain John McEnroe said Wednesday. ``You're counting on Andre to pull out a couple of wins in singles and maybe pull out the doubles, too.''

The United States plays Spain in Santander, Spain, on July 21-23.

Agassi lost to Australia's Patrick Rafter in the Wimbledon semifinals on Friday.