Pettitte left the Yankees' game against the Cleveland Indians after being struck in the ankle by Casey Kotchman's one-hopper in the top of the fifth inning. Pettitte, exhibiting signs of pain, was attended to by the training staff and Manager Joe Girardi. He made one more pitch before Girardi pulled him.
The team said he will be placed on crutches with his foot in a boot.
It was the second blow to New York's starting pitching corps this week, with CC Sabathia going on the 15-day disabled list.