Venus Williams has withdrawn from next week's Los Angeles Open due to an injury on the left wrist, tournament organisers said.
"I regret not having the opportunity to compete in Los Angeles where so many of my friends and fans live," Williams said in a statement.
Williams, world-ranked number 32, also withdrew from this week's Acura Classic in San Diego.
She has played only eight tournaments in 2006 and had failed to defend her Wimbledon title when she was upset in the third round by Jelena Jankovic.
Williams, who has sustained three separate arm injuries, is now in danger of being unseeded at the US Open.