Stanford, CA (AHN) - The Bank of the West Classic lost some of its star power as Serena Williams withdrew from the upcoming tournament on Thursday.

Williams dropped out of the event, which is scheduled to begin Monday, because of a lingering thumb injury that has kept her out of every tournament since Wimbledon.

The thumb injury to one of the most well known tennis players on the women's circuit happened in a fourth round match at Wimbledon when Williams played against Daniela Hantuchova.

Williams won that match but then lost against Justine Henin in her subsequent match, eliminating her from the prestigious Grand Slam tournament. Her sister, Venus, ended up winning Wimbledon.

Despite the absence of Serena Williams, who is the ranked seventh in the world, organizers of the Bank of the West Classic said the tournament will still be an extremely competitive event.

"Even without Serena, the depth of this year's field is very strong," Adam Barrett, the tournament's director, said. "The overall balance from top-to-bottom should make for some very exciting tennis."

Barrett emphasized the event will still have 20 of the top 50 players on the women's tour playing with No. 8 Anna Chakvetdatzke as the leading the way.