IRVING, Texas – For the first time since the opening week of the season, center Phil Costa will practice but he is not guaranteed to return to his starting spot on the Dallas Cowboys offensive line Sunday at Baltimore.

“The offensive line is like every other position on our team,” coach Jason Garrett said. “We’re going to create competition. We don’t have a rule that says this guy was the starter and then he got hurt and you can’t lose your job to injury. We don’t have any of those rules. We’re going to make our best decision.”

It all might be moot, however, as Ryan Cook has a hamstring injury and wasn't working with the team during the portion of practice that was open to media Monday.

Costa aggravated a back injury that kept him out of three preseason games after just three plays in the Sept. 5 season opener at the New York Giants. Cook, who was traded to the Cowboys on Aug. 31, took over for Costa and has started the three games since.

Costa started every game last year for the Cowboys.

“What we have to do is watch him and see what his health is like and see what he’s able to do,” Garrett said. “He did a good job trying to come back from that injury late in training camp going into that Giants’ game. We’ve got to make sure he’s healthy first and foremost. If he is, we’ll make our next best evaluation from there.”