Contreras was behind the plate, and teammate Jordan Hicks hurled a sinker that went low and left. Contreras was unable to catch the pitch, and it hit the dirt before careening off his knee, protected by a shin guard.
Contreras attempted to go after the ball but was hobbling and clearly in pain.
Thursday marked Contreras’ debut with the Cardinals after seven seasons with the National League Central-rival Chicago Cubs. He is a three-time All-Star, including last season.
He went 2-for-4 with two runs before leaving the game. He was replaced by backup catcher Andrew Knizner.