Second seed Lindsay Davenport has withdrawn from this week's China Open with a back problem.
Davenport won the 49th singles title of her career at the Wismilak International in Bali at the weekend.
The American was one of five top 10 players scheduled to appear in Beijing, but now only Maria Sharapova and the Williams sisters are left in the draw.
And fifth seed Alicia Molik made an early departure after losing 7-6 (7-1) 6-7 (4-7) 6-4 to Mariana Diaz-Oliva.
Molik is on the comeback trail after missing most of the season through injury.
Venus Williams warmed up for the event by beating Sharapova 6-4 6-4 in an exhibition in Seoul.