due to the round robin and most sets won format of play. Serena Williams won all three of her early round matches before enjoying a day off from play Friday.
The Williams sisters are also entered with each other in the doubles competition and will be in doubles action after suitable rest following their singles' semifinals.
Not before 6:30am PST USA, Venus Williams is to meet Jelena Jankovic of Serbia in semifinal number one. Number two ranked Serena Williams, who is set to reclaim the world's number one ranking next week, takes on Caroline Wozniacki of Denmark in the second semifinal.
The 8th ranked Jankovic found herself in a slump this season after turning in several subpar performances. But the Serb leads the 7th ranked Williams head to head 5-4 and had won five of their last six matches before Williams took their last encounter 6-2, 2-6, 6-3 exactly one year ago at the WTA Tour championships in this very round.
The pair's last eight matches have gone three sets. Williams' 2008 Wimbledon singles title gave the American her 7th career singles grand slam title. Jankovic reached the 2008 US Open final in her best grand slam performance to date.
Serena Williams, ranked second, leads the fourth ranked Wozniacki head to head 1-0 after winning their only prior meeting in January at the Sydney quarterfinals 6-7(5-7), 6-3, 7-6(7-3).
Williams took the Australian Open and Wimbledon titles earlier this year to raise her career singles grand slam won total to eleven. In her best grand slam result to date, Wozniacki reached this year's US Open final in September before falling to the eventual champion, Kim Clijsters of Belgium in straight sets.
Should both Williams sisters win today in singles, they would then face off for the second time of the week in Sunday's championship final.