* Phil Costa's status for Seattle game in doubt

IRVING, Texas – Phil Costa's MRI conducted Thursday revealed nothing new, according to source, but the Cowboys are not sure he will be able to play Sept. 16 at Seattle.

When Costa first suffered his low back strain in training camp, he missed two-plus weeks of on-field work and three preseason games.

If Costa cannot play, then Ryan Cook would start and the team would likely activate David Arkin for the first time. Arkin played center in Costa’s absence during training camp and in the preseason but was inactive for Wednesday’s win against the New York Giants.

Arkin was inactive for every game as a rookie as well.

“Arkin made great strides in this off-season and throughout training camp and the preseason,” coach Jason Garrett said. “For him to come in and play center after not playing center really throughout this whole career was really impressive. But at the end of the day, we felt like the more veteran player (Cook) was going to help us more in a game like this, and sure enough, he came in and played.”