Lee was taken to the locker room in the first half of the game and ruled out for the rest of the contest.
Lee has battled injuries for much of his career. He played in only 11 games last season, and only six the season before.
When healthy, Lee is a key player for the Dallas defense. Last year, he recorded four interceptions, 99 combined tackles and one touchdown. In three games in 2015, Lee has 33 combined tackles.
The Cowboys led the Saints 10–7 at halftime.