Williams is recovering from a bone bruise in his right knee, and was able to practice in a limited capacity on Friday. If he is unable to play, Maurice Hurt will likely fill in.
Strong safety Brandon Meriweather, who has not played yet this season, is listed as probable for Sunday. Madieu Williams has played the first three games in Meriweather's place.
Two wide receivers -- Pierre Garcon (foot) and Brandon Banks (hip) -- are also listed as questionable. Garcon has not played since Week 1, when he caught four passes for 109 yards. Banks caught one pass last weekend against the Bengals.
Running back Evan Royster (knee) and wide receiver Leonard Hankerson (back) are both listed as probable.
Finally, backup cornerback Cedric Griffin will not play: he is out with a hamstring injury.