LeSean McCoy questionable for Sunday's home game vs. Patriots

ORCHARD PARK, N.Y. -- Buffalo Bills star running back LeSean McCoy was limited in practice Friday, but coach Rex Ryan said he's "cautiously optimistic" that McCoy will play Sunday at home against the New England Patriots.

McCoy is officially listed as questionable. On Thursday, Ryan "backed him out" of practice because of hamstring tightness.

Ryan said Thursday that rookie Karlos Williams would be the next player up if McCoy was unable to play.

"Shady, he's gonna go. He's gonna be able to go," Williams insisted after practice Friday, using McCoy's nickname. "It's Shady. He's a big-time player who makes big-time plays. He's not gonna miss a game like this. So there's no doubt in my mind he's gonna go."

Still, Williams said he had no clue how effective McCoy can be.

"Workload, you have no clue. You don't know how it's gonna go when he gets into the game. Obviously he hasn't been feeling well, but I know he's gonna go out there and play," Williams said. "I guarantee he's gonna be 100 percent on Sunday by recuperating. He's got a couple of days here, today and tomorrow to make sure he's prepared to go."

McCoy suffered the left hamstring injury during training camp.