Cardinals first baseman Allen Craig twisted his left ankle while rounding first base and left the game in the fourth inning on Wednesday night.
Craig hit a grounder to Reds first baseman Joey Votto, who threw too high to pitcher Bronson Arroyo covering the base.
Craig twisted his ankle while rounding the base and fell hard, allowing the Reds to retrieve the ball and tag him out while he was still down.
He got up and walked off slowly. Matt Adams replaced him in the field.
The Cardinals have been bothered by nagging injuries while losing five of their last six games.
Right fielder Carlos Beltran missed two games with a stiff back, and catcher Yadier Molina left one game with a sore left wrist.