Barkevious Mingo has been hospitalised overnight with a bruised lung which he sustained during the Cleveland Browns' pre-season win over the Detroit Lions.
The linebacker, who was the sixth overall pick in this year's Draft, initially left the game with a bruised rib.
After the game, head coach Rob Chudzinski told reporters: "Barkevious Mingo has a bruised lung. We will keep him in the hospital overnight as a precaution and we will see tomorrow where he is at. I am not sure exactly how it happened. I am not sure."
The 22-year-old recorded 38 tackles and 4.5 sacks during his final season in college.