Veteran Kyle Williams is "50/50" to return this season from his knee injury, coach Rex Ryan said on Saturday.
Ryan is hopeful next week the team will have a better gauge of where Williams is in his recovery, but the 10-year veteran is apparently in danger of not returning.
"I know he's frustrated," Ryan said. "He was doing really well. Kind of had a setback, but we're not sure how much that's going to set him back."
Asked if he's confident Williams will return by the end of the season, Ryan said he's hopeful but added "Maybe 50/50 on if he will or not."
Williams originally left Buffalo's 34-21 loss to Cincinnati on a cart after a teammate rolled up on his knee.
In his place, as the season progresses, Corbin Bryant, Alex Carrington and Stefan Charles could all play roles next to Marcell Dareus on the defensive line. Bryant has 21 tackles this season, while Carrington and Charles have six apiece.
"Guys are doing a good job," Ryan said. "Carrington, I'm happy he's back. He seems to be healthy, obviously with Corbin and then Stefan Charles, even though he wasn't active last week. I think those guys have done a pretty good job."
Losing Williams would be a blow to the defensive line. Even at 32 years old, he was playing well before the injury with 14 tackles and one sack. The previous two seasons, he had 16 sacks.
Elsewhere, Ryan still has hope that safety Aaron Williams (neck), who's on injured reserve with designation to return, could play in 2015.
"I know he's starting to move a little bit," Ryan said. "He still looks a little stiff. Clearly, he's not ready to go for the next several weeks. But we'll see, hopefully by the end of the year he'll be coming back."
Otherwise, the Bills are a very healthy team. Guard Richie Incognito is listed as questionable on the injury report, but Ryan said he will play. And safety Leodis McKelvin and running back Karlos Williams, who had illnesses this week, are good to go and not even listed on the injury report.
"We're ready to go," Ryan said. "I like the fact that everybody's coming back, man. We're healthy as we've been all season. We still have a couple good players out but we feel good."
Out: DT Kyle Williams (knee)
Questionable: G Richie Incognito (shoulder, limited)
Probable: T Cyrus Kouandjio (knee, full)