But while the Cowboys will be without one of the leaders of their defense, another leader, DeMarcus Ware, says the team is not planning any changes.
"As our defense says, we’re going to do what we do. No matter who’s out there, you need to know how to do it and do it effectively."
Lee, who is in his third year out of Penn State, led the team in tackles with 58 before having his season ended by a toe injury. In the season opener against the Giants, Lee had 12 tackles and a forced fumble.
The Cowboys defense has been inconsistent in 2012. It has allowed at least 27 points in all three of its losses, but has held opponents to 17 points or less in its three victories.