"Vikings running back Adrian Peterson is listed as doubtful for Sunday's game at Atlanta because of a high ankle sprain, but apparently the injury report doesn't do Peterson's injury justice.

Coach Leslie Frazier calls him "very, very doubtful."

Despite Peterson telling coaches Thursday that he'll be ready to play, his limitations have become too obvious to ignore.

"When he got up on his toes to plant or make a cut, that's where he had trouble," Frazier said about Peterson's work with the training staff Friday. "That being the case, it's doubtful he'll be able to get to the point where by Sunday he'd be able to get out there. But we'll see."

Peterson appeared during the early portion of Friday's practice in uniform but without a helmet. He exited the fieldhouse a few minutes later with a trainer.

Frazier encountered Peterson's predictable toughness Thursday in the team cafeteria - "Coach, I'm a fast healer; I'll be ready," Frazier recalls the running back telling him - but Peterson hadn't fully tested the ankle's strength by then.

Peterson turned his ankle when his toe got stuck in the Metrodome turf on a 12-yard run late in the first quarter of Sunday's 27-21 loss to the Oakland Raiders.

Lateral movements are a problem for Peterson, who wore a protective boot until Thursday and has spent time rehabbing in a pool.

Frazier sounds optimistic for Peterson's chances next week against Denver. "