Moustakas suffered a left forearm injury in Game 1 of Sunday's doubleheader against the Tigers and isn't starting in Game 2, Bobby Nightengale of The Cincinnati Enquirer reports.
Moustakas was hit by a pitch in the sixth inning of Sunday's first game and was subsequently removed. He'll be replaced at second base in Game 2 of the doubleheader by Christian Colon, who is batting seventh. Whether Moustakas will be available for Monday's game against Cleveland remains to be seen.