Running back LeSean McCoy was not on the field during the open portion of Thursday's Bills practice after sustaining a hamstring injury Wednesday that put his availability for this week's game in question.
Receiver Robert Woods (foot) and defensive tackle Marcell Dareus (hamstring) were also absent Thursday, though left tackle Cordy Glenn (ankle) and tight end Charles Clay (ankle) returned to practice.
Coach Rex Ryan said McCoy felt tightness in the hamstring Wednesday and didn't finish practice, though several teammates said they didn't realize he had left. McCoy missed time last season with a left hamstring strain, though it's not yet known which side he injured Wednesday.
If Woods can't play Sunday, the Bills receiving corps would be comprised of Marquise Goodwin, Justin Hunter, Walt Powell and Brandon Tate. Ryan has said previously that the team also has plays for running back Reggie Bush to be used as a slot receiver.
If McCoy doesn't play, Mike Gillislee, Bush and rookie Jonathan Williams would lead the Bills' rushing attack.