Manager Aaron Boone said after Wednesday's win over Baltimore that McMahon is slated to undergo X-rays on his left thumb, Bryan Hoch of MLB.com reports.
McMahon injured his hand while sliding into second base in the second inning, and he was eventually pulled in favor of a pinch hitter in the eighth. The fact that he was able to remain in the game for several innings after injuring himself is encouraging, though the Yankees will presumably wait to see the results of the 31-year-old's X-rays before determining his availability for Thursday's series finale.