While the Pro Bowler was in a T-shirt and shorts and riding an exercise bike while reporters were present at Friday's practice, the Bills listed Williams as a limited participant on their injury report.
Linebacker Nigel Bradham (knee) is also doubtful. Like Williams, he was listed as a limited participant in Friday's practice despite not being spotted by reporters during their period of availability.
Both Bradham and Williams were listed as "did not participate" in practices Wednesday and Thursday.
If Williams doesn't play, the Bills are expected to use a combination of Corbin Bryant and Stefan Charles in his place alongside Marcell Dareus. Rookie Preston Brown is expected to start in Bradham's place if he cannot play.
Meanwhile, the Bills declared starting left guard Chris Williams (back) and special teams ace Marcus Easley (knee) as out for Sunday's game. Rookie Cyril Richardson is expected to make his second consecutive start in Williams' place.
Running back Bryce Brown, who was not on the practice field when reporters were present Friday, was not on the injury report.
Here is the Bills' full injury report:
WR Marcus Easley (knee; did not participate)
G Chris Williams (back; did not participate)
DT Kyle Williams (knee; limited participation)
LB Nigel Bradham (knee; limited participation)
CB Ron Brooks (shoulder; limited participation)
LB Randell Johnson (knee; limited participation)
WR Sammy Watkins (ribs; full participation)
WR Marquise Goodwin (concussion; full participation)