RIVER FALLS, WIS. ? That thick gray hair that once topped Gunther Cunningham’s stern visage has turned youthfully dark.

Now if Kansas City’s former defensive coordinator and head coach — who has returned to the defensive coordinator job — can pull one more miracle out of his bottle, the team that fired him three years ago could be headed to the Super Bowl.

All he has to do is take the NFL’s worst defense and make it good.

He must do this with virtually no significant personnel upgrade from last season’s woeful defense. He must do it right now before offensive standouts such as Priest Holmes, Tony Gonzalez and Trent Green go into decline and that elusive “window of opportunity” slams shut.

And one more thing: The proud, gruff-voiced German native must achieve all this while closing his mind to the unpleasant fact thad during his last year in Kansas City in 2000, he was a media laughingstock who was fired in humiliating fashion.

Can Gun pull it off? Will his gruff-voice-hides-a-warm-heart style wear thin, as it appeared to do while going 16-16 in the 1999-2000 seasons as head coach?

Or will he prove himself a gridiron sage by molding champions out of a group that failed to force even one punt from Indianapolis in a playoff loss last January?

“When you’re a defensive coach your whole life and you come back in this job, it’s kind of exciting. It’s all about organization,” Cunningham said. “This is about coaching players. That’s what I am, a football coach. I’m glad that I’m back. I missed this place, and I missed these people.”

Dick Vermeil insists that his predecessor was his first choice when Greg Robinson and his unpopular defensive scheme were terminated after the Indianapolis debacle ruined a 13-3 regular season.

Kansas City defensive coordinator Gunther Cunningham, left, and head coach Dick Vermeil look out over a recent Chiefs practice. Cunningham, a former Chiefs head coach, returned in the offseason to revamp Kansas City's porous defense.

“It was the only call I made,” Vermeil said.

Now after three successful seasons as linebackers coach at Tennessee, Gun’s back.

“It’s a definite confidence boost,” defensive end Eric Hicks said. “It’s still going to be a cleansing process, us getting rid of all those old techniques because we did them for so long.”

The differences in defensive philosophy between Cunningham and Robinson are stark. By the end of last season, many players were openly questioning Robinson’s ideas.

“Gun’s scheme is more attack, and Greg’s scheme was more read-and-react,” Pro Bowl safety Jerome Woods said. “I think we’re going to be more attacking. On defense, you don’t want to sit back and let the offense dictate what you do. We’re going to go out and set our own tone. I think everybody is excited.”

Vermeil admits he took special care to make Cunningham’s improbable return as painless as possible.

“He’s only human. I think it takes a heck of a man to respond like he did, to accept an opportunity to come back and not be over-sensitive about it,” Vermeil said. “It also shows the organization has a lot of respect for him.”

The few veterans who were here back in the good old days when Cunningham ran his attacking defense seem delighted to embrace an old friend.

“He’ll scream at you, but for a reason,” said Hicks, who had a career-best 14 sacks under Cunningham in 2000.

“There’s definitely sincerity there. When he’s cussing you he really means it. But when he’s putting his arm around you, he means that, too.”

Cunningham, 57, was 16-16 as head coach in 1999-2000 but seemed to lose control after a series of news conference gaffes and questionable game-day decisions.

There is no denying that the Chiefs’ defense was among the finest in the NFL while he was coordinator in 1995-98.

They were 42-22 during that span and allowed an NFL-low 1,050 offensive points. Twice they led the league in scoring defense. In 1997, when the Chiefs went 13-3, Cunningham’s defense broke a 63-year-old league record by not allowing a second-half touchdown in 10 straight games.

But those teams had players like Neil Smith, James Hasty, Dale Carter and the late Derrick Thomas — Pro Bowlers every one of them.

This defense has only one, Wood.

“We have a great offense and a great kicking game, and as a defense we just have to try to get on that same plane,” Cunningham said. “It’s not always about the stars. It’s about the team when you’re playing football. These kids, they’re willing. And that’s the main thing.”