Williams, disappointed to miss out after making her debut in the event last year, said she experienced pain in her knee last week after returning to her normal practice schedule.
"My medical advisors and physio have recommended that I refrain from competition until I am pain free," Williams, whose sister and world number one Serena will not be competing, said in a statement released by the organizers.
Story continues below ↓advertisement | your ad here"Unfortunately, I am not at a point where I can commit to competing next week."
Despite losing Williams, the event still boasts eight top 10 players on the WTA Tour, and 26 of the Top 30, including defending champion and top seed Jelena Jankovic, defending U.S. Open champion Kim Clijsters, and three-time grand slam champion Maria Sharapova.
The main draw action begins on Monday with the final on August 15. The men's tournament takes place the following week and features Roger Federer, Rafael Nadal and Andy Roddick.
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