"He said it was his jaw," Girardi said. "He felt like his jaw got jammed. And then in talking to him later when he came in, in the sixth, he said he felt a little foggy. He was having a hard time putting words to it, so I helped him. I said, 'You're out.' He didn't want to come out, but I said, 'You're out.'"
Francisco Cervelli pinch-hit for McCann in the sixth inning and remained in the game as the Yanks' catcher.
McCann finished 1-for-2 with a walk on Friday and is batting .238 with 13 home runs and 49 RBIs in 103 games this season, his first in New York. Girardi said McCann will be evaluated again on Saturday.
Last month, the Yankees placed outfielder/designated hitter Carlos Beltran on the seven-day disabled list after Beltran sustained a concussion and fractured his nose in a batting practice mishap. Beltran returned after the seven days and has not felt any symptoms since.
Even though Beltran said he was fine after the incident, the Yankees wanted to handle him with caution. Girardi said he plans to do the same with McCann.
"I'm not sure what it means right now," Girardi said. "We've got to go talk about it obviously. We'll probably have to make a decision about something."
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. Jamal Collier is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.