The Cowboys will strongly consider signing a veteran center in the near future. Phil Costa (back) is doubtful for Monday night's preseason opener against the Raiders, but he is expected to be able to practice next week. Dallas backups Bill Nagy and Kevin Kowalski out indefinitely due to ankle injuries. "There's a chance that we'll have (a center) in here tomorrow," Stephen Jones said after Saturday's practice. "That's something we're looking at doing -- getting a little insurance -- but we really feel good about Costa."