Title holder and top seed Amelie Mauresmo received an easy passage into the final of the Advanta Championships in Philadelphia on Saturday when Maria Sharapova was forced out of the event with a sore shoulder.

The Wimbledon champion and third-seeded Sharapova injured her shoulder two weeks ago at the Swisscom Challenge in Zurich and aggravated it during her quarter-final victory over Australia's Alicia Molik on Friday.

Frenchwoman Mauresmo now meets sixth-seeded Russian Vera Zvonareva, who progressed with a 6-3, 7-6 win over compatriot Nadia Petrova.

The eight-player field for next week's WTA Tour Championships in Los Angeles was finalised on Friday when Jennifer Capriati and Venus Williams crashed out in the quarter-finals, allowing Zvonareva and Serena Williams to clinch the last two berths in the lucrative $3 million season finale.

The six players who had already secured places were world number one Lindsay Davenport, U.S. Open champion Svetlana Kuznetsova, French Open winner Anastasia Myskina, Elena Dementieva, Mauresmo and Sharapova.