Cowboys owner Jerry Jones was already worried about the interior offensive line and holding its breath about whether it would hold up in front of quarterback Tony Romo.
And that was before center Phil Costa left practice on Friday with a back injury. David Arkin took reps in his place on the first team.
The Cowboys don't believe the injury is serious but it came at a bad time with just one practice remaining before the preseason opener against the Raiders.
It's also another setback for the interior offensive line that is already without three players because of injury in guard Bill Nagy (ankle), center Kevin Kowalski (ankle) and guard Nate Livings (hamstring). Guard Mackenzy Bernadeau returned to practice this week for first team after being undergoing hip and knee surgeries in the offseason.
The Cowboys have not decided if he will play against the Raiders as they choosing to remain cautious.
It all Jones admittedly frustrated.
"I think frustration is probably good in this case," Jones said. I must tell you that I am holding my breath a little bit because I need the interior of this line to be a source of confidence for Tony and to feel good about his protection in there. We can talk about the running game. I know that helps protect him in our passing game. But I look at it principally by it beginning with protection for him. That’s got me a little angst right now, but I am liking some of the things I am seeing in there, although Costa raised his head late out here in the afternoon, but I don’t know how serious it is."