Venus Williams, the 2001 and 2000 US Open champion, has withdrawn from this year's tournament with a persistent stomach muscle injury.
She joins her younger sister, Serena, who beat her in last year's final at Flushing Meadows, in missing the year's last Grand Slam. Serena withdrew after undergoing knee surgery.
Venus sustained the injury at a tournament in Poland in April and was troubled by it at the French Open in June. She played at Wimbledon, but needed treatment to the injury in the final, which she lost to Serena.