Broncos starting running back Montee Ball will undergo a magnetic resonance imaging exam on his strained groin Monday morning.

The initial belief is Ball will be “out for a while,” according to an NFL source.

Ball rushed for only 7 yards on six carries Sunday against the Arizona Cardinals before he went down with a groin injury while blocking in the third quarter on Peyton Manning’s 20-yard completion to Emmanuel Sanders.

Ball ran for 5 yards on the previous play before going down with the injury. Ronnie Hillman and Juwan Thompson then got hot, combining for 80 yards rushing the rest of the game.

Hillman rushed for 65 yards on 15 carries in the second half, and Thompson rushed for 15 yards on three carries, including an 8-yard touchdown run that was the first score of his career.