Merrill was scratched from the lineup for Thursday's game in Colorado due to right groin tightness, Manny Randhawa of MLB.com reports.
Padres manager Mike Shildt said the move was precautionary and Merrill could have played, so it sounds safe to call the rookie outfielder day-to-day. Jose Azocar will shift over to center field, Tyler Wade will move to left and Eguy Rosario will enter the lineup at third base.