There is no clear indication when the injury happened, but Lee left the field for further examination in the team's locker room. He appeared to be in pain and was struggling to put weight on his left leg. Lee recorded three tackles in the first half and was a key player in stopping Saints tight end Jimmy Graham.
Lee entered Sunday's game with 90 tackles and four interceptions. His absence will lead to the Cowboys' defense turning to fourth-year linebacker Kyle Bosworth. A career special teams player, Bosworth has six tackles in 2013.
Drew Brees and the Saints offense attacks the center of the field with a series of quick routes and seam passing to Graham. The Cowboys defense is vulnerable without Lee on the field and it will be interesting to see if this becomes a factor moving forward.