Detroit Lions defensive end Cliff Avril left the game against Minnesota in the third quarter with a head injury.
Avril was shaken up on Minnesota's first possession of the half. The Lions say he is being evaluated for a possible concussion.
He was listed as questionable on Friday with a back injury, but was able to start the game against the Vikings. He made an impact in the first half when he batted a pass by Christian Ponder back into the quarterback's arms and tackled him for a 15-yard loss.
Lawrence Jackson was getting the bulk of the work in Avril's place.
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