Vikings Pro Bowl running back Adrian Peterson practiced on a limited basis Wednesday because of a back injury. On Thursday, he said his back is "not a big deal at all."

"God willing I'll be out there playing," he said about Sunday's home opener against the 49ers.

Peterson actually began his weekly press conference with a joke about it. Knowing the question would come, Peterson told reporters he had a "weak back right now."

Asked if it happened on one particular play, Peterson said, 'It happened like a week back. But it's all behind me."

All that was missing was the rim shot.

"You liked that, huh?" Peterson said, smiling.

Middle linebacker E.J. Henderson also was limited because of a shoulder injury, but defensive coordinator Leslie Frazier said he thinks Henderson will be able to play Sunday.