Cowboys may have to start center who never snapped

The Dallas Cowboys are heading into their preseason opener with the distinct possibility of starting a center who had never snapped the ball before getting to training camp a couple of weeks ago.

Starting center Phil Costa missed practice Saturday because of a lower back injury that forced him out of practice the previous day.

David Arkin, a guard drafted in 2011 who didn't play last season, was playing center with the first-team offense and snapping to quarterback Tony Romo.

The Cowboys have been decimated by injuries in the interior line. Kevin Kowalski and Bill Nagy, the other players who had been expected to compete with Costa at center, were already out because of ankle injuries.

Dallas plays its preseason opener Monday night at Oakland.