FRISCO, Texas -- The Dallas Cowboys will be without two starters on defense in linebacker Sean Lee and safety Jeff Heath on Sunday against Philadelphia and could be without left tackle Tyron Smith for a second straight game because of a groin injury.

Despite Jason Garrett saying Smith would get work in Friday’s practice, he missed his sixth straight day of practice since being forced out of action late in the Nov. 5 win against the Kansas City Chiefs. He is listed as questionable, just like last week, although the Cowboys ruled him out before traveling to Atlanta.

If Smith can’t play, then Byron Bell would start at left tackle over Chaz Green, who gave up four of the eight sacks the Cowboys allowed last week to the Atlanta Falcons. The Cowboys will see how Smith handled the work Friday and will see how he works out before the game before making a final decision.

“We would never put a player out there who’s not able to function and protect himself,” Garrett said. “We’ll just see how he does and keep making our evaluations as we go.”

Lee will miss his third game of the season with a hamstring strain and it is likely he will not play again until Dec. 10 against the New York Giants.

Heath is officially listed as questionable, but a source said he would not play. Without Heath, rookie Xavier Woods would start. Woods had the first interception of his career last week and has been credited with 17 tackles by the coaches with three pass deflections.

“A really instinctive player, doesn’t seem like the situation is too big for him, someone who learns from his experiences both on defense and in the kicking game and a guy who’s comfortable and confident in playing,” Garrett said of Woods. “He’s a physical player. He’s made some plays on the ball. He’s made some tackles, and he’s one of those guys that with the work that we’ve given him, he’s taken advantage of. You want to see more of him.”