The Vikings insist they will not decide whether Adrian Peterson will play in the season opener against Jacksonville until Sunday morning. But what the star running back, who had left knee surgery nine months ago, is able to show in practice this week will go a long way toward influencing that decision.

Coach Leslie Frazier cleared Peterson for full contact Wednesday and Thursday, wanting to see how Peterson responds to the contact, both while it's happening and when the day is done.

"We're going to try to give him as much as we can," Frazier said. "We've got a few plays designed for him in practice. And we'll see how he responds and see what he has to say tomorrow when he comes back."

The official injury report said Peterson was limited at practice. And Frazier said Peterson wouldn't be tackled to the ground.

"What's going to happen on Sunday, we can't simulate in practice at all," Frazier said. "It wouldn't be wise."

Eventually the Vikings coaching and medical staffs will have to make a leap of faith to clear Peterson for game action.

Said Frazier: "It will be the same, even if we waited a week from now, three weeks from now; it's hard to simulate a game in practice. It's almost virtually impossible. So it won't necessarily be a leap of faith. It will be based on what our medical staff says, what our coaches see and what Adrian feels as well. We'll try to gather that information and make the right decision."

Mularkey looking back New Jaguars coach Mike Mularkey didn't back away Wednesday from the comments he made to a Jacksonville paper this week about the locker room selfishness that affected the last two Vikings teams he played on (1987-88).

"We had a roster full of [talent]," said Mularkey, who played tight end for the Vikings from 1983 to '88. "We were very talented. Some of the things that went on behind the scenes, it was frustrating in our locker room at times for some players to watch situations take place. I'm not going to point out situations or the players or what they were. But we should have won more games than we did, and I think a lot of things that played into it took place in the locker room. You're talking 30 years ago now."

Mularkey has been coaching in the NFL the past 28 years. He said those experiences and the "selfishness" he saw in those locker rooms in 1987 and '88 have helped mold him as a coach.

"It's hard to explain it without giving you exact examples, but I know I wasn't the only one affected," Mularkey said. "I know the guys in the locker room that sat there and sweated out making the team every year -- and there were a bunch of us in that locker room -- it was frustrating at times to see what was going on in that locker room, to watch things happen as they did."

Etc. Jerome Simpson, signed to be the Vikings' deep threat in the offseason, will sit out the first three games because of an NFL suspension. The wide receiver is allowed to be in the locker room at practice but can't be on the field.

"I'm counting down the days," Simpson said. "Right now, it's all about the team. But I'll be itching to get back."

Brandon Fusco will start at right guard on the revamped offensive line.

"When it comes time to play, there will be some butterflies," the second-year pro from Slippery Rock said. "But still, it's a player's game. You line up where the coaches tell you and do your job. Play physical, and play fast."

Fusco, who is 6-4, said he started college weighing 230, but is at 305 six years later.

• Rookie safety Harrison Smith said he's ready for the NFL season after playing for Notre Dame last year.

"At the end of the day, it's football, no matter what the time or the day," he said. "You know everything will be faster ... you just have to roll with it."

• The Wednesday injury report said linebacker Marvin Mitchell, safety Andrew Sendejo and receiver Jarius Wright (all ankle injuries) did not participate in practice. Cornerback Marcus Sherels (ankle) was limited.