The Yankees may need to figure out a temporary fix. Posada left Friday's game at Fenway Park in the bottom of the fourth inning with a bruised left thumb and could miss the remainder of the club's series against the Red Sox.
Backup Wil Nieves came into the game as a replacement and caught the final five innings, but Nieves has not had a Major League hit since 2002 and is 0-for-9 this season.
The emergency options currently on the Yankees' roster would include first baseman Josh Phelps, a former catcher, or utility man Miguel Cairo.
"It's a ticklish situation when you're dealing with your catcher," Yankees manager Joe Torre said. "We're thinking a day, maybe two days. We have to make a decision on having Phelps as a backup or doing something else. We haven't made that decision."
Posada, 36, suffered the injury while catching a pitch from New York starter Andy Pettitte, the Yankees said.
Posada went 1-for-2 on Friday, doubling off Red Sox starter Curt Schilling in the fourth inning to raise his batting average to .352 and extend his current hitting streak to 10 games.
Posada also has two home runs and 11 RBIs this year, having played in all 15 of the Yankees' games.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.