Update: LeSean McCoy returned and started the second half of Sunday's game.
McCoy broke loose on a long run and was in the second level before collapsing before the first down marker. The non-contact injury appeared to be a hamstring, as he grabbed at his leg and remained down on the field for some time before being helped off the field by trainers. McCoy was massaged on the sideline, but left the field and went to the team's locker room for further evaluation.
The loss deals a big blow to the Eagles offense. McCoy ran for 37 yards and a touchdown against the Redskins on Sunday and has run for almost 1,000 yards this season. Much is made of the team's quarterback position, but the running back is what makes Chip Kelly's offense tick.
Running back Bryce Brown will play in McCoy's absence. He has totaled 163 yards rushing this season.