Mathieu suffered a shoulder subluxation mid-game against the Panthers on Sunday, NFL Network Insider Ian Rapoport reported.
Sitting at 3-4-1 at the halfway mark of the season, the loss of Mathieu hurts a Cardinals secondary that has been up and down in 2016. The Honey Badger recently shifted to spending most of his snaps at slot corner.
Mathieu hadn't returned to the MVP-caliber play we saw early in 2015, but his absence will be felt in a shallow defensive backfield. Safety Tyvon Branch was previously placed on IR and could be a candidate to return in early December depending on Mathieu's recovery.
The Cardinals are so beat up that Arians said he wouldn't conduct practice during their bye week. Arizona will instead watch film and try to rest.