Sean Lee is scheduled to have his left knee operated on this Thursday, Dallas Cowboys head coach Jason Garrett announced Tuesday. And while there was no set timetable given for Lee's return, the team is holding out hope he will be able to play this coming season.

The standout middle linebacker sustained the injury on the first day of OTAs on May 27.

The Cowboys continue to maintain that this is essentially a torn ACL. According to sources, however, that Lee was informed that the damage sustained could be more serious than that.

The team has option of putting Lee on the physically unable to perform list, giving him the chance to still play this season, though things will be more certain after Thursday.

"We'll see what that surgery indicates and we'll make our decisions from there," Garrett says.

A source close to Lee says he is likely to have Dr. Dan Cooper perform the procedure, which under most circumstances is season-ending.