ALLEN PARK, Mich. (AP) -- Detroit Lions running back Zach Zenner is going on injured reserve with cracked ribs and a partially collapsed lung.
Coach Jim Caldwell said Monday that Zenner was in the hospital after being injured in Sunday's overtime win over Chicago. Caldwell said Zenner would go on IR "at some point in time" but that his condition was improving.
Zenner has 60 yards on 17 carries this season. He impressed during preseason and has received some playing time in a backfield that's been hurt by Joique Bell's injury problems and Ameer Abdullah's fumbling.
Theo Riddick made the most of his opportunities Sunday, running for 28 yards on seven carries and catching three passes for 50 yards.