The Packers list Williams (concussion) as out for Sunday's game against the Cowboys, Rob Demovsky of ESPN.com reports.
After exiting the Packers' Week 4 loss to the Eagles on Thursday following a hit to the head, Williams was unable to partake in practice at any point this week. He'll thus miss his first game of the season while he remains embedded in the concussion protocol, leaving rookie sixth-round pick Dexter Williams and fullback Danny Vitale as the lone depth options on the roster available behind lead back Aaron Jones.