According to the Dallas Morning News, Lee is expected to be out anywhere from four to six weeks, which means he's not expected be back on the field until Week 14 (Dec. 9) at the earliest. If the hamstring doesn't heal quickly, Lee could be out until Week 16, which mean's he wouldn't be playing again until Dec. 23.
The linebacker injured his left hamstring during the third quarter against the Titans, and after the game Cowboys coach Jason Garrett made it pretty clear that Lee wouldn't be coming back anytime soon.
"We anticipate him to be out for a little bit," Garrett said, via ESPN.com. "No question about that."
The injured hamstring is another setback for Lee, who's been battling injuries for most of his nine-year career. As a matter fact, Lee actually injured the same hamstring during a 24-13 loss to the Seahawks back in Week 3. After suffering that injury, Lee sat out three games before he was finally able to return in Week 7. However, the linebacker was unable to stay healthy. After a Week 8 bye, Lee injured his hamstring again against the Titans.
The injury-plagued Lee has never played an entire 16-game schedule for the Cowboys. The linebacker has missed a total of 45 out of 136 games since being selected by the Cowboys in the second round of the 2010 NFL Draft. Lee missed five games last season and also missed the entire 2014 season with a torn ACL. Over the years, he's missed games due to multiple ailments, including an injured toe, neck and wrist.
With Lee having trouble staying healthy, the Cowboys will now have to decide if they want to keep him going forward. Lee only has one year left on his contract and the Cowboys would actually save nearly $7 million in cap space if they were to release him after the 2018 season. The team has also been planning for the future at the linebacker position. In April, the Cowboys selected Lee's potential replacement, Leighton Vander Esch, with the 19th overall pick in the NFL Draft.