Winn was removed from Friday's game against the Red Sox after getting hit on the knee by a pitch, Jeff Jones of the Belleville News-Democrat reports.
Winn drew a walk in his first plate appearance before taking an 84-mph sweeper off his knee in the third inning. He was initially able to remain in the game but was eventually pulled when St. Louis took the field in the fifth. The Cardinals will likely send him in for X-rays to determine whether he suffered a fracture.