Despite coach Doug Pederson's assertion that Cox is "doing well," he'll be sidelined for a second straight week.
"It's Week 5 and we've got a lot of football left and he's progressing nicely so we've just got to be careful," Pederson said.
Beau Allen will replace Cox in the starting lineup.
Running back Wendell Smallwood also might miss Sunday's game. He suffered a knee injury against the Chargers and hasn't practiced all week. He's officially listed as questionable and was deemed a game-time decision by Pederson, but it's rare for a player not to practice during the week and then play on Sunday.
His absence would mean an increased workload for LeGarrette Blount and undrafted rookie free agent Corey Clement. Kenjon Barner, who signed just last week after Darren Sproles was lost for the season, could be the No. 3 option.
Blount has hit his stride of late and is coming off a 16-carry, 136-yard performance in L.A. He'll lead the charge against a Cardinals defense that ranks fifth in opponent yards per attempt (3.2).