Mountcastle, who was pulled from Saturday's game against the Giants after hitting a double in the second inning, is said to be dealing with left foot pain, Jake Rill of MLB.com reports.
Mountcastle was replaced on second base by Dylan Beavers after the former hurt himself on a stumble and dive toward second base after hitting a double. It's not clear how serious Mountcastle's injury is, but he exited the field with a trainer by his side.