(Eds: Updates with quotes, details. With AP Photos.)

By DAVE CAMPBELL

AP Pro Football Writer

EDEN PRAIRIE, Minn. (AP) - There's plenty of experience left in Minnesota's defense, despite the rebuilding project that has turned over so much the roster in the last year.

If a mini-Mount Rushmore monument were made for this group, the faces of veterans Jared Allen, Chad Greenway, Kevin Williams and Antoine Winfield would certainly be featured. The older guys are still significant if not critical contributors.

Look closely at the first four games for the Vikings, though, and their youth is revealed -- in a valuable, age-defying way. Balance between the three position groups is important for good defense, as is a mix of old and young. The Vikings have enjoyed both.

``We just make plays when they need to be made. We haven't made that big mistake,'' Greenway said.

The tackling has been better, as has the pass coverage, and the defensive line has applied enough raw pressure that blitzes haven't been needed a lot. As solid as the holdovers have played, particularly Greenway and Winfield, the source of the improvement can be traced straight to the newbies.

Rookie Josh Robinson, who has the team's only interception, has provided an obvious upgrade at cornerback in the nickel package. Jasper Brinkley has taken over as the starting middle linebacker without much trouble. Another first-time starter, Letroy Guion, has defended the run well at nose tackle, recorded two sacks and even blocked a field goal.

Then there's utility lineman Everson Griffen, emerging as a secret pass rushing weapon in his third season, and rookie strong safety Harrison Smith, who has given the Vikings the hard-hitting, smart, ball-hawking player they haven't had in years at that position.

These two guys have been making as big of an impact as anyone.

After ending their experiment with Griffen as a linebacker in training camp, the Vikings moved the 6-foot-3, 275-pounder back to his home on the line. He gives Allen and Brian Robison an occasional break at the end spots and usually replaces Guion inside when passing situations call for the nickel group. Griffen leads the team with three sacks and is tied for second behind Allen with six quarterback hurries, quite the production for a part-time player.

I like d-line. That's where I live. That's where I belong. It's doing me well,'' Griffen said.Whatever I can do to help this team win, that's the biggest thing.''

Defensive coordinator Alan Williams recalled watching video of last season on his first day on the job.

``There was a blur going across the screen and I was thinking, Is that a linebacker? Is that a safety running across the field?' And I went back and forth a couple of times and got my program out and looked at it, and it was Everson Griffen. I looked at his height and weight and I was thinking,Wow, we have something here,''' Williams said.

That's the same reaction Vikings coaches had when they first watched Smith in action during the practices leading up to the Senior Bowl in January. He hasn't disappointed, with 30 tackles, six passes defended and no glaring mistakes through his first four NFL games.

His best moment so far was probably last Sunday at Detroit, when he hit wide receiver Calvin Johnson so hard that the Lions star couldn't hang onto what would've been a touchdown catch late in the second quarter. The Lions had to settle for a field goal on that drive, and the Vikings won 20-13.

``We want people to have a second thought about us or not just think they're running free down our defense,'' Smith said.

Williams, paraphrasing his former boss in Indianapolis, then-coach Tony Dungy, called Smith ``the eraser'' for his ability to make up for other's errors in coverage or pursuit. Free safety Jamarca Sanford raved about his partner's instincts and intelligence.

You get a lot of rookies, they might know their assignment but they don't know what other guys are doing,'' Sanford said.And he's one of the guys who really knows what everyone's doing on defense.''

That's legitimate leadership, regardless of age.

I'm doing my job and working to get better every day. That's enough for me right now, and if that evolves into me leading or if people like how I play and kind of see that as leading then so be it,'' Smith said.But I'm not going to try to take over the room or anything.''

Notes: After sitting out the last two days because of a groin injury, Allen participated fully in Friday's practice. QB Christian Ponder (right knee) and WR Michael Jenkins (rib) did the same. Coach Leslie Frazier said all of them will be ``fine'' to play in Sunday's game against Tennessee. ... Marvin Mitchell, who has filled in for Erin Henderson at weak side LB, has a strained calf muscle and probably won't be available. Henderson will be back after missing the last two games with a concussion.

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