Damon bruised the shoulder and strained his left AC joint during a violent collision with the left-field fence. General manager Brian Cashman said it's "50-50" that Damon will return to the active roster when he is eligible to.
"It could be longer," Cashman said. "I certainly don't want to represent that he'd be ready in 15 days. It's probably a push."
Placing Damon on the DL now means that he could miss only three games as the All-Star break looms. To take Damon's spot on the roster, the Yankees called up outfielder Justin Christian from Triple-A Scranton/Wilkes-Barre.
"It's disappointing, but I knew the team needed to get another body up here because I couldn't promise when I could be ready," said Damon, who was batting .319 with six home runs, 37 RBIs and 50 runs scored. "I could have given it a couple of days, but the team would still be in a bind."
It's possible that Damon, who throws left-handed, will be able to hit before he can throw, and Cashman said he'd consider using Damon as a designated hitter. Damon said he may rehab in Tampa, Fla., as Yankee Stadium will be used during All-Star week.
Brett Gardner, who was called up on June 30, will get the majority of the playing time in left field, although manager Joe Girardi said that Christian will see some time.
"This is a great opportunity for Brett Gardner -- for instance, to feel relaxed and not feel like he's got to produce every time out," Cashman said. "You have to have depth, and hopefully, if you're a championship-caliber club, the depth will perform for you in the period they're asked to step up."
Willie Bans is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.