Cain had an MRI Monday after experiencing forearm tightness and is "iffy" for Wednesday's start, according to manager Bruce Bochy, the San Francisco Chronicle's Henry Schulman reports. Forearm tightness can be a symptom of a UCL tear, so this is definitely something to pay close attention to. If Cain cannot take the ball Wednesday, Tim Lincecum or a minor leaguer will take that turn in the rotation. Ryan Vogelsong has already been named the starter for Tuesday's game as Jake Peavy will miss at least one start with a back issue, but if Cain is out for a significant period of time, Vogelsong would likely just remain in the rotation once Peavy is healthy.