Moscow, Russia (AHN) - Russian star Maria Sharapova has withdrawn from this weekend's Fed Cup semifinal against the United States.

The world's No. 2-ranked player, who has yet to make her debut in the team competition, has a shoulder injury and has been told to rest for 10 days by doctors.

Sharapova has been struggling with the problem the past few months and left Wimbledon last week after getting defeated by eventual champion, Venus Williams, in the quarterfinals.

"All the scans and tests show improvement in my shoulder but I still have a tremendous amount of swelling in the area," she said on her Web site. "Since having cortisone shot in 2007 is not an option for me, I need to monitor my shoulder at all times.

"The good news is that Russia still has an amazing team and I believe they will still have a very good chance to win the match."

Elena Vesnina replaces Sharapova on the squad for the matches scheduled Saturday and Sunday at Topnotch Resort in Stowe, Vt.

Also due to shoulder pain, Russian number two Svetlana Kuznetsova has been described as "a long shot" to play.

The U.S. team is scheduled to include Serena and Venus Williams, who won Wimbledon last Saturday, and doubles players Lisa Raymond and Vania King. Serena Williams will reportedly shake off the calf injury she incurred against Daniella Hantuchova at Wimbledon and play the event.