Costa strained his lower back Aug. 10. He returned to practice Aug. 27 and played 12 snaps of the preseason finale against the Dolphins. But he lasted only three plays Wednesday.
Cook, acquired in a trade from the Dolphins on Saturday, played the rest of the game at center. He had been beaten out for the backup center job by undrafted rookie Josh Samuda in Miami and was destined for the waiver wire before the Cowboys relinquished a seventh-rounder for him.
"I thought our team handled that well," Cowboys coach Jason Garrett said. "First of all, that's the reason he is here. He is a veteran player. He is a smart guy. He has handled the ball a lot in his career, so we thought that was an important thing for us, and he went in and played like a veteran. I think the guys around him played well and communicated well. It wasn't perfect, but I thought they handled it as well as they could."
-- Charean Williams