Red Sox catcher Victor Martinez fractured the top of his left thumb against the Giants on Sunday.
He suffered the injury in Boston's 5-1 win and was replaced by Jason Varitek. A foul tip off the bat of Pablo Sandoval hit Martinez's left thumb in the second inning.
Martinez was hit on the thumb again in the third inning by a foul ball by Andres Torres.
"It's not a given that he'll go on the DL but it's not a given that he'll be OK, either," manager Terry Francona said. "We'll get him examined tomorrow and we'll see where we go from there."
Victor Martinez Breaks Left Thumb