Williams is expected to receive the initial snaps at running back Sunday against the Rams with Adrian Peterson (neck) unavailable, Kyle Odegard of the Cardinals' official site reports.
If head coach Bruce Arians had his druthers, he'd rely on one running back for the majority of the contest, be it David Johnson (wrist) or Adrian Peterson (neck). With the former on injured reserve and the other inactive, Williams would seem to be the first man up in the backfield. That said, Williams will be playing with cracked ribs, which could result in a trickle-down effect for the remaining RBs (D.J. Foster, Elijhaa Penny and Bronson Hill) on the active roster.