Venus Williams has withdrawn from next week's Los Angeles Open due to a left wrist injury, tournament organisers said on Friday.
"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 this year and 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 U.S. Open.
Williams's sister Serena and former number one Lindsay Davenport are still due to make their returns from injury in Los Angeles.