Kevin Youkilis left Monday nights game with a "jammed thumb," injured on a lineout in the bottom of the first inning.
Fluoroscope X-rays did not show a fracture, but the team will still send him to undergo an MRI on Tuesday, just to be sure.
After the game, Terry Francona said that Youkilis was "pretty sore."
"[H]e's had a bone bruise in that area and when he got jammed, that thing swelled up real quick and got discolored," manager Terry Francona said. "Sometimes, when you get jammed like that it can be as small as a broken blood vessel. It hurts like heck and then goes away."
If Youkilis does need to miss any time, the Sox have three first basemen in Triple-A: Lars Anderson (hitting .247/.338/.411/.749), Ryan Shealy (.239/.358/.485/.843 in Triple-A) and Aaron Bates (.230/.326/.351/.676). And Mike Lowell is still sitting on the disabled list, waiting to be activated.