Although the club hadn't made any official announcement, 27-year-old backstop Seby Zavala was spotted in the Sox dugout ahead of Saturday's matchup with the Tigers.
Grandal left the game Friday night with calf tightness, but still has yet to be involved in an official announcement regarding the severity or length of time he'll be out.
Zavala was hitting under .200 in Triple-A Charlotte. He had five home runs and 15 knocked in before he made the trip to the big club. The right-handed bat will act as the backup to Zack Collins for as long as the Grandal injury hinders the starting catcher's ability to play.