On Monday, when asked in an interview with ESPN whether he was the best in his position, Philadelphia Eagles rusher McCoy replied, "yes sir".
However, Peterson has stated that McCoy himself does not believe his own answer, with the Vikings man declaring that McCoy will need more conviction in his words if he is to be taken seriously next time.
"He didn't really mean it," Peterson told Fox Sports Radio. "If you watched his response, he didn't mean it.
"I've got to give the young guy credit because there is nothing wrong with having confidence in yourself. But you've got to speak it with more truth. He's a heck of a running back and I like his style, so I won't get on him too much.
"But it was funny because when he was asked the question, he kind of hesitated, and he didn't believe it when he said it. I always tell the youngsters, 'Say it with your chest, like you mean it', and I don't think he did."
Peterson is widely recognised as the best in the business having run for 2,097 yards total during the 2012 campaign, although he rushed for 341 yards fewer than league leader McCoy last term.