A swollen bursa sac in Marion Barber's left knee is slowing the Cowboys running back.
The injury limits Barber's range of motion, causing him discomfort as he tries to make a move and accelerate, which is why he was limited to three carries and 4 yards in Saturday's wild-card victory against Philadelphia.
Barber played mostly in the first quarter and a few series, but he did not see any time in the second half. As he walked to the locker room after the game, he was noticeably limping. Barber's absence meant a career-high in carries (16) and yards (148) for Felix Jones and 14 carries, his most since Week 4, for Tashard Choice, who gained 42 yards and scored a touchdown.