D'Andre Swift's availability for Week 11 is in doubt.
The Detroit Lions running back is dealing with a concussion issue and did not practice Thursday.
Swift was not on the injury list Wednesday.
The rookie running back is coming off his best game of the season in his first career start, earning 149 scrimmage yards on 21 touches with a TD catch. Swift's speed and quickness to the edge brought a needed element to the Lions backfield last week versus Washington.
The Lions planned to give the rookie more work down the stretch of the season as the primary back.
The concussion issue could be a big setback for a 4-5 Detroit squad looking to get to .500 against a 3-7 Panthers team that could be without star running back Christian McCaffrey and quarterback Teddy Bridgewater on Sunday.
If Swift isn't cleared through protocol -- and it's pretty late in the week to just be getting diagnosed -- Adrian Peterson would likely regain the starting gig. Kerryon Johnson, who has been mostly an afterthought, would likely also see a boost in snaps if Swift is out.