Williams missed Sunday's 24-7 victory against Detroit that improved Carolina to 2-0 with a thigh injury that flared up after Wednesday's practice.
Without him, the Panthers rushed for only 62 yards, the team's fewest since Week 10 of the 2012 season when it had 52 yards on 21 carries against Denver. Thirty-seven of those came from Jonathan Stewart, and 22 of those came on one run.
"It was a tough day,'' Carolina coach Ron Rivera said on Monday.
Rivera hopes Williams, who led the team in rushing with 72 yards on 14 carries in the opener, will provide a boost. If anything, he will restore depth to a unit that saw Mike Tolbert suffer a shoulder contusion in the second half and Fozzy Whittaker go down with a quad injury.
Rivera said Whittaker would be listed as week to week. Tolbert appears all right.
Quarterback Cam Newton jokingly limped into the locker room when he noticed reporters watching him. Newton underwent offseason ankle surgery in March and fractured his ribs during an Aug. 22 exhibition game that forced him to miss the opener at Tampa Bay.
Rivera said Newton's foot was a little sore, actually calling that a good thing.
"Because it’s more sore than his back,” Rivera said. “Which is good. At least, I think it’s good. He’s moving around pretty good and he’s feeling pretty good about himself.
"I thought he played a heckuva football game.”
Newton completed 22 of 34 pass attempts for 281 yards and a touchdown. He also rushed four times for 19 yards.