The official diagnosis was a torn ACL, and the four-time Pro Bowler had surgery in December to repair the ligament.
"He's not like most running backs that I've been around through my career," Spielman told ProFootballTalk.com on Thursday. "He is just a freak athletically and you can see that in his rehab and how quickly he's coming back from this ACL and I know he wants to go out there and prove to everybody he’s a better Adrian Peterson than he was before the injury."
Peterson signed a seven-year, $96 million contract last September, which means the Vikings could have a difficult decision on their hands if their star is slow to return to form. In 2013, Peterson's salary is set to jump from $8 million to $11.25 million.
That's superstar money for a player who now must prove he still warrants the designation.