Venus and Serena Williams have withdrawn from the doubles competition at the Australian Open, shortly before their first-round match was scheduled to be played on Friday.
Tournament officials said the sisters pulled out because of an injury to Venus' lower left leg.
The announcement came shortly after Serena Williams, a five-time singles champion in Australia, won her third-round singles match against Daniela Hantuchova in temperatures of almost 40C (104F).
The Williams sisters have combined for 13 career Grand Slam doubles titles. They were unseeded at Melbourne Park after only playing four tournaments together last year.