Minnesota Vikings head coach Mike Zimmer is confident that running back Adrian Peterson will recover from groin surgery to make an impact in the 2014 season.

Peterson had a down year by his standards in the 2013 campaign as he rushed for 1,266 yards along with 10 touchdowns, 800 yards fewer than his 2012 season.

Zimmer told reporters: "This guy isn't an average 28- or 29-year-old back.

"This guy is special and some of the things, when we were fixing to play him, some of the things that I thought, I watched him and I was like, 'Wow, if we're not really good in the way we line up and contain and be in the right positions, we're going to have a hard, hard day.'"

Zimmer became head coach of the Vikings in January after Leslie Frazier was fired.