"I feel like that extra day is going to help him," Girardi told MLB.com. "He wants to play, but to be on the safe side, let's see if we can give this another 24 hours."
Posada, 38, was injured during Wednesday's game against Texas, when a foul tip nicked his glove. In the meantime, the Yankees medical staff has equipped him with a "contraption" resembling a wrap, which is meant to dull the pain in time for Sunday's game.
The time off is doubtlessly necessary for the catcher, but that doesn't mean he's happy about it.
"I think he wants to play every day," Girardi said. "I think he wanted to play [Friday]."
Jose Molina has taken over catching duties since the injury.
In 89 games this year, Posada is hitting .277 with 17 home runs and 63 RBIs.