Carolina's all-time leading rusher, with 6,733 yards, hasn't played since spraining his ankle in the first half of a Sept. 28 loss at Baltimore. Before that, Williams missed two games with a hamstring injury.
"It'll be a nice boost," Rivera said. "When he and Jonathan [Stewart] get rolling and doing the things they do, that's a huge thing for us. That could be a nice shot in the arm."
Stewart, who has missed three games with a knee injury, had a season-best 79 yards on 16 carries in Sunday's 13-9 loss to the Seattle Seahawks.
Having both backs for a key NFC South game in which the winner will emerge in first place could be key. The Panthers are 3-4-1, mere percentage points ahead of the Saints at 3-4.
"It will help a lot just to complement Stewart," offensive coordinator Mike Shula said of having Williams back. "When we're rushing the ball effectively, it's usually with those two guys."