The women take centre stage at the US Open today when Kim Clijsters meets Maria Sharapova and Mary Pierce takes on Elena Dementieva for a place in the final.
Belgian fourth seed Clijsters, who has won six titles in 2005, has lost in four grand slam finals, while Russian top seed Sharapova will be appearing in the last four at Flushing Meadows for the first time.
The two have met three times before, with Clijsters coming out on top each time, including a straight-sets win over the Russian in the final in Miami earlier this year.
Sharapova will regain the world number one ranking from American Lindsay Davenport next week, win or lose against Clijsters.
Pierce, the 12th seed, has not dropped a set in reaching the semi-finals for the fourth time while sixth seed Dementieva, the runner-up last year, upset second seed Davenport in the previous round.
Dementieva has won both of her previous meetings with Pierce but the Russian will be hoping for an improvement on serve, having committed 62 double faults in her opening five matches.
