Hayes is out of the lineup for Friday's game against the Padres with a lower-back injury, Jason Mackey of the Pittsburgh Post-Gazette reports.
Hayes went 0-for-5 with an RBI and two strikeouts Wednesday against the Rockies, and it's unclear when he picked up the injury. He should be considered day-to-day until the team updates his status. Rodolfo Castro will move to the hot corner while Diego Castillo is starting at shortstop.