Realmuto was removed from Saturday's game against Atlanta due to lower-back tightness, Charlotte Varnes of The Athletic reports.
It's unclear when the injury occurred, but Rafael Marchan entered the game for Realmuto as a pinch hitter in the sixth inning. Realmuto dealt with a sore foot about a week ago, though the issues don't look to be related. The severity of Realmuto's current injury is unclear.