David Johnson underwent surgery that is expected to keep him out up to 12 weeks.
David Johnson, an All-Pro selection at the "flex" position last season and considered among the best running backs in the league, was injured late in the third quarter of Sunday's season-opening 35-23 loss at Detroit when he made a catch and was hit hard at the 3-yard line.
The Cardinals have been in a situation like this before, Arians said.
Chris Johnson needs 463 yards to become the 30 running back in National Football League history with 10,000 career rushing yards.
The Cardinals had released Chris Johnson in their final roster cuts this year.
While many believe the Cardinals' postseason chances are all but gone because of losing their best player, if they can stay in the mix or even earn a playoff berth, Johnson's return could give them fresh legs for a postseason run. Williams finished with five carries for 10 yards and a touchdown.
Chris Johnson, who missed almost all of last season with a knee injury, rushed for 814 yards for Arizona two years ago. Foster made the Patriots roster a year ago as an undrafted free agent.
"It's always a huge blow to lose a top player", Arizona coach Bruce Arians told azcentral.com.