The team's all-time leading rusher missed last week's 24-7 victory over Detroit with what has been called a thigh injury, but he clarified on Friday that it's a hamstring injury. He also was limited in practice much of this week and continues to be listed as questionable.
But Williams took reps with the first team on Friday and appears ready to go, barring a setback.
Coach Ron Rivera said he's most concerned about starting wide receiver Jerricho Cotchery (hamstring), who did not practice Friday and is listed as questionable. He said Cotchery ran on the treadmill in the pool and will be re-evaluated on Saturday.
Cotchery said he likely will be a game-time decision, adding he's not so much worried about playing against his former team as he is being ready for the long haul.
Rivera said no decision has been made on whether to bring a player up from the practice squad to take defensive end Greg Hardy's spot on the 53-man roster. Hardy on Wednesday was placed on the commissioner's exempt list until his domestic violence case is resolved.
The decision to use the spot will be determined by the injury situation. Rivera said running back Darrin Reaves or one of two wide receivers -- Stephen Hill or Marcus Lucas -- could be brought up.
Rivera also said there's a chance that spot is left open for defensive end Frank Alexander, who's set to return on Sept. 29 from a four-game suspension for violating the league's substance abuse policy.