LONDON -- Former champion Lindsay Davenport withdrew from Wimbledon Tuesday after failing to sufficiently recover from knee surgery.

Davenport, who won in 1999, had surgery on her right knee in January and has missed the Australian Open and French Open, causing her to drop from No. 1 to No. 6 in the WTA world rankings.

"I am extremely disappointed not to be able to play on the grass at Wimbledon this year,'' the 26-year-old American said. "I really hoped I could make it back from my surgery earlier than expected and be able to play at Eastbourne and Wimbledon but it is just not possible yet.''

Davenport said she was optimistic she'd be ready for the hardcourt season, starting in July. Tony Godsick, her agent, said Davenport is scheduled to play at the Bank of the West event in Stanford, Calif., on July 22.

Davenport underwent surgery after damaging cartilage in her right knee in the semifinals of the WTA Championship in Munich last November. She missed nine weeks last year with a similar injury.

Davenport was a semifinalist at Wimbledon last year, and a finalist the year before. She also won the U.S. Open in 1998 and the Australian Open in 2000.

Fellow former champion Martina Hingis, who won in 1997, withdrew from Wimbledon last week after undergoing surgery last month to repair ligaments in her left ankle.

Two-time Wimbledon finalist Arantxa Sanchez-Vicario has also pulled out citing "extreme exhaustion.''

Wimbledon runs June 24-July 7.