Pittsburgh Steelers' first-round pick Derrick Harmon is expected to be sidelined for about a month with an MCL sprain, sources told NFL Network's Ian Rapoport.
The injury makes the defensive tackle a candidate to begin the season on injured reserve, Rapoport adds.
Harmon suffered the injury during the team's final preseason game against the Carolina Panthers on Thursday night. He was carted to the locker room after his knee twisted awkwardly on a pass-rush snap. However, he later returned to the sideline in street clothes.