Williams hasn't played a tournament since defeating her younger sister Serena to win her fifth Wimbledon title earlier this month.
"I have been receiving treatment for tendinitis in my right knee over the last several days and my medical advisers have encouraged me to allow myself an additional week to completely recover,'' she said in a statement.
Williams said she still plans to play the Rogers Cup in Montreal, the Beijing Olympics and the U.S. Open this summer.
Davenport's nagging right knee injury caused her to withdraw from a tournament for the fourth time in seven weeks. She is on the U.S. Olympic tennis team.
"I always look forward to the opportunity to play so close to home, but unfortunately my knee has not completely healed at this point,'' she said in a statement.
Meng Yuan of China moved into Williams' spot in the draw, while Stephanie Dubois of Canada took Davenport's place. Serena Williams is scheduled to play in the $600,000 Carson tournament that begins Monday.
INJURED TIGER SETS SIGHT ON RECORD
Venus, Serena, Sharapova head U.S. Open field
