Yankees Manager Joe Girardi told reporters after the Yankees' 3-2 victory over Baltimore Wednesday that Posada was absent due to "concussion symptoms" from taking a foul ball off the mask during Tuesday night's loss.
Posada was taken to NewYork-Presbyterian Hospital during the game after complaining of feeling "foggy." Girardi said the catcher tested negative for a concussion and had been cleared to play.
"I saw him today and asked him how he felt," Girardi told MLB.com. "He said he didn't sleep a whole lot last night and he had somewhat of a headache, but I heard him laughing in the (players') lounge. That made me feel better. Jorgie has one of those laughs that carries."
The Yankees' skipper said the team is very wary of possible concussions to players, especially because they can have longlasting effects.
Minnesota Twins slugger Justin Morneau has been out since July 7 after suffering concussion symptoms sustained when he slid into second base to break up a double play in Toronto.