FRISCO, Texas – Tyron Smith sat out of practice Thursday morning, casting further concern over the status of his back injury.

Smith was limited in Wednesday's practice, three days after he started in the Cowboys' win against Cincinnati on Sunday. The issue must have flared up after Wednesday's workload, as he wasn't present for the second practice of the week.

That has to be concerning for the Cowboys, who were also without Chaz Green at Thursday's practice. The second-year tackle is still coping with a foot sprain he suffered on Oct. 2 against San Francisco, and his absence puts the team without two of its top three tackles for the time being.

On the brighter side of things, Dez Bryant was on hand for practice for the second-straight day. Bryant worked into individual drills and was a limited participant in Wednesday's practice. Cowboys coach Jason Garrett said he was hopeful Bryant could do more as Sunday draws closer.

"He participated in the walkthrough and we'll see what he's able to do today," Garrett said.

The Cowboys also returned David Irving to practice for the first time in two weeks. Irving suffered a concussion in the San Francisco game and had been out for almost two weeks. With Irving returning and DeMarcus Lawrence upping his participation at practice, the Cowboys should have their full complement of defensive linemen Sunday against Green Bay.

Morris Claiborne was also at practice on Thursday, one day after rolling his ankle in practice. Garrett said he doesn't think Claiborne's injury is serious.

Orlando Scandrick once again sat out of practice on Thursday, putting his status for Sunday in doubt. Scandrick hasn't played since Week 2 against Washington, as he has been coping with hamstring issues for the past three weeks.