IRVING, Texas -- With George Selvie slowed by a thumb injury, Anthony Spencer could make his first start since 2012.

Spencer has played in nine straight games in a reserve role after missing the first three contests as he worked his way back from microfracture knee surgery that limited him to just one game last season. Spencer has yet to start a game at defensive end in his career with the Dallas Cowboys using him as an outside linebacker in their 3-4 scheme from 2007-12.

Spencer has 20 tackles but just a half sack to go along with 11 quarterback pressures and a tackle for loss.

Coach Jason Garrett said he believes Spencer is past the part of managing his health.

"He's had a role that we hope that can be increasing," Garrett said. "He's been part of rotation. I think at different games he's showed up. Other games he hasn't been quite as effective. But he's a good football player and I think he's learning to play this scheme as he goes. He's been a stand-up outside linebacker for most of his pro career so I think getting him down into his stance and getting him comfortable down in and down out doing what the job requires has been a process but in certain games he's shown up, other games not quite as much. We certainly need him down the stretch."

Rookie defensive end DeMarcus Lawrence was on the practice field after injuring his ribs in Monday's practice, which left him limited for the session. The Cowboys do not believe it will bother Lawrence for Thursday. Selvie was also limited on Monday.

On Tuesday, the Cowboys were without the same three players who missed practice on Monday: safety Jeff Heath (thumb), cornerback Tyler Patmon (knee) and linebacker Dekoda Watson (hamstring).