Video (02:40) : Adrian Peterson isn't happy about the trash talking the Rams did to him the last time they played and Cordarrelle Patterson said he's constantly thinking about his first kickoff return opportunity in the season opener against the Rams.

You won’t find it on a sign, in a playbook or as part of any Vikings code of on-field conduct. But if you’re a defender at Winter Park, you know the rule.

“I would say it’s one of the unwritten rules,” defensive end Brian Robison said. “Bottom line, in practice, stay away from Two-Eight.”

That would be No. 28. Adrian Peterson.

But sometimes there is a significant problem with that rule. It begins with the fact that Peterson is possibly the NFL’s most physical player and ends with the fact that he loves turning his 6-1, 217-pound frame into a contact-seeking projectile that’s too darn fast to avoid, even in practice.

“That’s the thing,” safety Harrison Smith said. “Sometimes, when there’s a collision, it’s because we’re trying to move and he won’t let us.

“You can kind of tell when he’s fed up with not having any contact. That’s when he’ll start running at you instead of away from you.”

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With no preseason action, virtually no practice contact and Sunday’s regular-season opener at St. Louis only two days away, Peterson definitely has reached Defcon 1 when it comes to his desire to smash someone. And he admits there are times in practice when he crosses the line.

“It’s kind of like a one-sided thing,” Peterson said of the unwritten no-contact rule. “A lot of defensive players come to me and complain about it because I do look for contact, so I kind of give the guys a shoulder or two from time to time. I know guys like Harrison Smith, he’s not going to back down, so it kind of rubs him the wrong way sometimes. He voices it to me. Nothing that he’s mad about, but it is what it is.”

Peterson calls himself a “savvy vet” who now understands the “big scheme” behind not playing in the preseason. He hasn’t taken a hit since Dec. 22 at Cincinnati, but isn’t concerned about the rust factor.

“Honestly,” he said, “I’m able to make the transition pretty quick.”

You can say that again. A year ago, Peterson sat out the preseason and responded by turning the team’s first snap of the first regular-season game into a 78-yard score at Detroit.

Peterson said he told teammates four days before the game that he’d score a touchdown on his first carry. Asked if he’d like to “call his shot” again Sunday at St. Louis, Peterson thought for a second and then took the bait.

“Yeah, I might as well speak it,” he said. “Yeah, touchdown. First run.”

That’s sure to rankle the Rams. Then again, they also rankle Peterson.

Two years ago, as he fell 8 yards short of Eric Dickerson’s NFL single-season rushing record of 2,105, Peterson ran for a season-high 212 yards at St. Louis on Dec. 16.

But it was the Rams who had the upper hand early in that game. Peterson lost yardage on four of his first five carries and six of his first eight. After seven carries, he had zero yards.

Peterson said the Rams started “yapping,” causing him to yap back, which is something he said he’s never done except for that game.

“Those guys had me so hot,” Peterson said. “I haven’t ever been that mad playing football.”

On his ninth carry of that game, Peterson broke off a career-long 82-yard touchdown run. And, yeah, he let the Rams know how good it felt as the game unfolded and the Vikings won to keep their playoff push alive.

“Normally, I’m an assassin out there,” Peterson said. “I was a talking assassin that time. Those guys were talking so much noise. Then we ripped a long run on them and things got quiet. Hopefully, things play out the same way [Sunday].”

With 10,115 yards rushing, 91 touchdowns, six Pro Bowls, three first-team All-Pro honors and a league MVP on Peterson’s résumé, teammates embrace the Bubble-Wrap philosophy when it comes to the star running back and practice.

“He takes enough hits on Sundays,” Robison said. “He also hits them before they hit him, too.”

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In the preseason, it’s Matt Asiata who takes the first-team hits. But even he is cool with the unwritten rule.

“It’s a good approach for us,” he said. “We keep him under wraps so we can unleash the beast when the lights come on.”