Mariano Rivera still hasn't been able to set a date for surgery to repair the torn ACL in his right knee he suffered in Kansas City earlier this month, because the blood clot doctors discovered following the injury hasn't dissipated. "We're trying to work out the clot," said Rivera, who remains on medication to get rid of the clot and is rehabbing the knee in the meantime. "I have to strengthen the knee. I'm doing a lot of therapy." The hope is the rehab will help offset the delay of the surgery. Because the Yankees don't expect Rivera back before next season, manager Joe Girardi is confident Rivera's return won't be affected by the clot.