Posada was catching in the eighth inning when a foul tip off the bat of Nelson Cruz clipped his glove, aggravating an injury that has nagged the 37-year-old backstop for the better part of two weeks.
He walked out to the mound in pain and was lifted by manager Joe Girardi as a precaution, with a nod to the lopsided score. X-rays taken at Yankee Stadium were negative, but Posada is expected to be sore.
"It's been beat up before, and it just took another hit today to the same spot," Posada said. "It was a little bit more painful than I thought it would be."
It is believed that Posada injured the finger originally on Aug. 12 at home against Toronto, and has been using ice since then to alleviate some of the swelling.
"That's part of the trade as a catcher," Girardi said. "You get foul tips and it seems like you're getting something healthy and it gets hit again. There's a little concern that he's going to be extremely sore. Hopefully they'll get the soreness out as quick as they can."
Posada said that the finger bothers him more catching than hitting -- he belted a three-run homer in the second inning off Texas' Derek Holland to give the Yankees a lead.
He suggested that the Yankees might tape it under his glove, but there are few other options.
"I don't think it's going to heal until the season is over," Posada said. "The joint is bruised and there's not much I can do. I can ice it and ice it, but I feel it, especially catching."
Posada was not expected to catch Thursday anyway, with a day game being scheduled in the Bronx.
Also Wednesday, Alex Rodriguez was hobbled after fouling a ball off his left foot but remained in the game another half-inning before leaving. Girardi said that Rodriguez would have precautionary X-rays taken but noted he had run the bases fine.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.