Detroit Lions coach Jim Caldwell said the tailback was hospitalized Sunday night with multiple cracked ribs and a partially collapsed lung. He'll be placed on injured reserve, which ends his season.
Zenner suffered the injury on a second-quarter run in the 37-34 overtime win against Chicago. He was examined at length on the field, then again on the sideline, before returning to the locker room.
Zenner, an undrafted rookie out of South Dakota State, captured the imagination of fans during a breakout training camp. He won over the Lions, too, once he led the NFL in rushing during the preseason.