The Buffalo Bills are concerned LeSean McCoy may not be ready to play in Week 1 due to his left hamstring injury.

McCoy suffered the injury in practice on Aug. 18.

McCoy's MRI showed, what was described internally as, a "small tear," adding: "They say it tore in a spot where it couldn't have been any better for us. It tore in a spot that is kind of high up, surrounded by stronger muscles in the glutes and things like that."

McCoy is not at full speed in practice but is doing rehab work including light footwork, agility and cardio conditioning, but there is concern he won't be in great "football shape."