Molina pulled his left hamstring sliding into the plate in the fourth inning Sunday night and could be headed for the disabled list, further thinning out the Yanks' already-depleted catching ranks.
Posada replaced him in the eighth and the Red Sox stole two bases without a throw - Posada said he was under orders to hold the ball. Coco Crisp, who nabbed one, said Boston was aware that Posada had an injured shoulder.
"They told me not to throw," Posada said. "Jose was hurting, so it was a matter of sucking it up. I'll throw (today)."