BALTIMORE -- Yankees first baseman Mark Teixeira left Friday's 6-5 loss to the Orioles in the third inning with discomfort in his right knee.
Teixeira was examined by an Orioles team physician and left Camden Yards for an MRI. Results of the MRI were not immediately known.
Manager Joe Girardi said that while Teixeira has been dealing with pain in his right knee this season, Friday was the first time that it locked up.
"It's a different feeling now," Girardi said. "It wasn't locking up then. It's something he's dealt with before, and today he said he felt it a little bit."
Teixeira has also battled neck spasms and missed four games May 25-28 as a result. On Friday, he grounded to first in a second-inning at-bat to drop to 3-for-43 since May 17.
"I don't know if it happened jogging out in-between [innings]," Girardi said, "or if it happened running to first, but he said it locked up."
Should Teixeira miss any significant time, the Yankees will find themselves in a serious predicament. The club is extremely thin at the first-base position, with Greg Bird and Dustin Ackley having both undergone season-ending shoulder surgeries.
• Ackley has season-ending shoulder surgery
Rarely is a 36-year-old first baseman hitting .180 with three home runs and 12 RBIs so hard to replace. The Yankees, though, are limited. So how might Girardi fill the potential void?
"I have no idea," he said. "I have to go talk to my general manager."
The short-term fix may be utility infielder Rob Refsnyder, who took over at first base Friday and cleanly fielded the two ground balls that were hit to him.

Refsnyder, 25, has been taking grounders at first base during batting practice over the past few days, but he said he has never played the position regularly. The last time he even played the position sparingly, he said, would have been at the University of Arizona, where he played from 2010-12.
"What I'm focused on now," Refsnyder said, "is just getting game reps and getting as comfortable as I can. ... If that's what Joe needs, that's what I'll do."