Lions RB Zach Zenner will miss the rest of the season with multiple cracked ribs and a collapsed lung, according to the Detroit News' Josh Katzenstein.  It's a tough break for a rookie who impressed this preseason and was starting to see a bigger role.  We'll see if Joique Bell (Achilles) can return this coming week as Detroit's "big back."  The entire backfield is in flux with RB Ameer Abdullah struggling with fumbles and suffering a stinger yesteday.

Lions RB Zach Zenner exited in the 1st half of Sunday's game with a chest injury.  His return is officially questionable.  Detroit is already without big back Joique Bell.

Update: Zenner was ruled out for the rest of the game at halftime.

Lions RB Joique Bell (ankle) has been ruled out for Monday night's game against the Seahawks.  We don't have any details about his injury, but he didn't practice all week, so he's certainly not a lock to return for Week 5.  Bell's absence on Monday should mean a bigger workload for RB Ameer Abdullah.  It makes him a low-end RB2 in a difficult matchup.  RB Zach Zenner also figures to see some action but can't be trusted in fantasy lineups.

Lions RB Joique Bell ran with the 1st-team offense in his return to practice on Monday. "I did everything with the ones," Bell said. "I was limited, as far as reps, but I did everything. Everything from team blitz to regular team."  Consider this a case of veteran deference.  This is Bell's 4th year with Detroit, while his backfield competition consists of a couple of rookies.  "Bell remains the Lions' No. 1 tailback — for now, at least," insider Kyle Meinke writes.  Touches remain up for grabs in this backfield, and our money is on the fresh, explosive Ameer Abdullah winning the majority of them this season.  Bell might even lose some work to rookie Zach Zenner, who's been ultra-impressive this preseason.  The Lions RB situation will be worth tracking closely early on this season.

Undrafted free agent RB Zach Zenner latched on with the Lions.  Zenner hails from South Dakota St. but gained a cult following in the pre-draft process thanks to an impressive combination of production and measurables.  He posted 3 straight 2,000-yard rushing seasons with 58 TDs over that span.  He also caught 77 balls during that 3-year stretch.  Then Zenner checked into the Combine at 6'0, 223 pounds and ran a 4.60-second 40-yard dash with a 41-inch vertical and 121-inch broad.  That gave him the 2nd highest SPARQ score in this year's RB class -- behind new teammate Ameer Abdullah.  Detroit's backfield is currently a bit crowded with the 2 rookies, Joique Bell and Theo Riddick.  But Bell turns 29 in August and Riddick only looks like a pass-catcher.  Zenner is capable of emerging as a "big back" complement to Abdullah down the road.