Ellington was injured in the fourth quarter on Sunday without being hit. He went to ground and had to be helped off the field before a cart carried him to the locker room.
Ellington headed into this season as Arizona's No. 1 running back after accounting for more than 1,000 yards from scrimmage each of his first two seasons. He ran for 660 yards and had 395 more in receptions last season despite missing the final four games because of injury.
Arizona signed three-time Pro Bowler Chris Johnson during training camp to add depth to its running back group.
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