Mariano Rivera was unavailable on Wednesday night due to tightness in his left groin. Rivera has been dealing with the tightness for a while, but the Yankees don't believe it will be an issue as long as he gets a few days of rest. "We're going day by day," Rivera told MLB.com. "Hopefully, [I can pitch] as soon as possible." Rivera pitched on Monday and Tuesday, and originally felt the tightness on Aug. 15 at Seattle. "It's a concern for you to run him out there," manager Joe Girardi said. "We don't want to hurt him. We'll probably give him a few days off and see if we can nip it."