Kim Clijsters pulls out of U.S. Open with an abdominal injury . Two - time defending champion Clijsters ' withdrawal is likely to leave Serena Williams as a warm favorite to add to her grand slam tally , but the American was herself forced out of the latest WTA event in Cincinnati through injury , but it is not thought serious . Williams has reached final four grand slams of tennis . Clijsters sustained the injury in the Rogers Cup in Toronto last week . Maria Sharapova advances into semifinals in Cincinnati to play Vera Zvonareva .
Kim Clijsters pulls out of U.S. Open with an abdominal injury . Two - time defending champion Williams has reached final four grand slams of tennis . Clijsters sustained the injury in the Rogers Cup in Toronto last week . Maria Sharapova advances into semifinals in Cincinnati to play Vera Zvonareva .