Vikings running back Adrian Peterson and wide receiver Percy Harvin are questionable for Sunday's game against the Bills. Peterson has a sprained right ankle and Harvin is dealing with migraines yet again. Minnesota coach Leslie Frazier said he was optimistic that Peterson will be able to play after he practiced on a limited basis Friday. "We're still going to take him out on Sunday morning, just to see how he moves around, make sure he's confident in what he has to do to play in the game," Frazier said. "He did a much better job than we thought he would today, so we're optimistic."