Pettitte was struck by a ball off the bat of the Indians' Casey Kotchman in the fifth inning of New York's 5-4 win, forcing him to leave the game. He is wearing a boot to protect the ankle from further injury, but the Yankees said that surgery is not believed to be necessary, and he could resume throwing in four to six weeks.
"We'll get him back. That's a good thing," general manager Brian Cashman said. "It's not something that he's gone for the year on. Hopefully we'll have some meaningful games to play in October and we can look back and say he was fresh for it. We've got to obviously win a lot of games between now and that point."
Pettitte was in obvious discomfort as he threw several warmup pitches after the injury, but he convinced manager Joe Girardi that he could stay in the game. Pettitte threw just one pitch, a strike, to Lou Marson, before Girardi came back out of the dugout and escorted the limping Pettitte off the field.
"I just figured I would figure out a way to get through the inning," Pettitte said. "Even though I knew I couldn't push off like I wanted to, I just figured I would go the other direction with it -- throw it slower than slow, maybe get them to hit some grounders.
"But that first pitch I threw, I pushed off, and [there was] just a lot of pain shooting right into my foot. I knew I wasn't going to be able to throw another pitch."
As Pettitte was trying to shrug the pain off, putting on a good show for Girardi and assistant athletic trainer Mark Littlefield, his teammates weren't fooled and could tell that bad news was on the horizon.
"I told [Robinson] Cano when he was warming up, 'There's a pretty good chance we won't see him until after the All-Star break, and maybe it's a little worse than that," third baseman Alex Rodriguez said.
The injury made for a double-whammy afternoon in which the Yankees announced they plan to place ace left-hander CC Sabathia on the 15-day disabled list with a left groin strain, which Sabathia suffered on Sunday against the Mets at Citi Field.
"It's not what you're looking for, I can tell you that," Girardi said. "When I came to the park, I felt pretty good about the way we've been playing. CC's hurt and now Andy's hurt. But no one's going to feel sorry for us and guys have to step up, that's the bottom line."
New York had planned to have veteran Freddy Garcia pitch in Sabathia's place on Friday, but Garcia was needed for 2 1/3 innings of relief on Wednesday because of Pettitte's early exit.
Triple-A Scranton/Wilkes-Barre right-hander Adam Warren will instead make his Major League debut on Friday against the White Sox, with Garcia set to start on Monday against the Rays in St. Petersburg.
Warren is set to join the club on Thursday to get acclimated to Yankee Stadium, and Cashman said the Yankees also will call up reliever Ryota Igarashi for immediate bullpen help. David Phelps, who threw 55 pitches in his last outing at Class A Tampa, will also be a candidate for promotion shortly.
"These guys are going to get an opportunity to step up," Girardi said.
Yankees catcher Russell Martin liked what he saw this spring from Warren, who is 5-5 with a 3.86 ERA in 15 starts at Triple-A.
"I saw him quite a bit. I was pleased," Martin said. "He's professional. You feel like he has good command of at least three pitches, understands how to pitch. We'll see what we have when he gets here. I haven't seen him in a while, but I like his stuff."
After missing all of the 2011 season, Pettitte came out of retirement this spring and rejoined the Yankees on May 13. He was making his ninth start of the season and is 3-3 with a 3.22 ERA.
"We've just got to weather the storm," Pettitte said. "Nobody's going to feel sorry for you with injuries and stuff like that. We've got a lot of good stuff going on here. We've got plenty of guys who can step in and do the job, so it's time to put my pom-poms on and be a cheerleader now for six weeks or so."