Yankees left-hander Andy Pettitte was forced to leave his start against the Mariners on Thursday after 79 pitches with an apparent undisclosed injury. Pettitte appeared to stiffen and wince after throwing his final pitch, a swinging strikeout of Kyle Seager for the second out of the fifth inning. Yankees manager Joe Girardi dashed to the mound and held a fairly lengthy conversation with Pettitte, who shielded his mouth with his glove. Pettitte jogged off the field and was relieved by Shawn Kelley. Pettitte allowed two runs and four hits in his outing against Seattle, with three walks and five strikeouts. He entered play on Thursday with a 4-2 record and 3.83 ERA in seven starts.