River Falls, Wis. ? Gunther Cunningham, the hard-driving, perpetually sleep-deprived defensive coordinator of the Kansas City Chiefs, trudged slowly toward the lunchroom.

Sorry, Cunningham said through heavy eyelids, no time now to chat. Maybe later. Too many things to think about. Too much to do.

Then he disappeared behind closed doors, but not without one peek into a troubled soul.

“I’d better not mess this up,” he said.

In total agreement will be about 80,000 excited fans packed into Arrowhead Stadium for the Sept. 11 season opener.

Also nodding yes are team president Carl Peterson, executive vice president Denny Thum, player personnel director Lynn Stiles, director of scouting Chuck Cook and all their assistants, interns, secretaries and scouts.

All those cogs in the Chiefs machine have done their jobs. They’ve received very high marks for a productive offseason geared toward turning a sorry defense into an ace.

Through both free agents and trades, they acquired cornerback Patrick Surtain and safety Sammy Knight from the Dolphins, and signed linebacker Kendrell Bell off the Steelers and defensive end Carlos Hall from the Titans. They also brought in free agent cornerbacks Ashley Ambrose and Dwayne Washington.

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And, hardly able to believe their luck, they grabbed Derrick Johnson with the 15th pick in the first round of the draft after figuring there was no way the Texas All-American still would be left.

That’s at least five new starters, all trying to learn a new scheme and get acquainted with each other and create that elusive, hard-to-define substance called team chemistry.

The front office has done its job. The rest is up to the players – and a grizzled coordinator with a raspy voice and a patch of gray stubble on his weathered, grandfatherly face.

“Sometimes I walk to my car and feel like I need an IV or something,” Cunningham said with a grin. “The scheme is being taught well by the assistant coaches. I’m real happy about that. But where we’re lacking is in fundamentals, the fundamentals of the game. That is really disappointing to me right now.”

Cunningham is not a man to take his sport lightly. A history buff and student of warfare, he recently read “The War Fighters,” a manual provided to U.S. Marines in Iraq, and was inspired to pass its message along.

“It talks about the brotherhood. When you go out there and fight for real like those fine young men and women, you’d better stay together,” he said.

“To me, that’s the most critical thing we have to do. We have to change the culture of the defense – the attitude we bring on the table, the brotherhood, the respect we have for each other.”

Improved tackling would also help.

Teaching such a thing to NFL veterans might seem akin to teaching Tiger Woods about the proper use of the sand wedge. But it has been an Achilles’ heel for the Chiefs for more than three years.

“There’s only one way to do it, and that’s to tackle,” Cunningham said. “The wrap-up you feel on the field, that’s live. Tackle! You don’t take the guy to the ground, but you wrap. What happens is you get your feet, you get your angles, you get your arms and body involved.”

A week into camp, things do seem to be coming together.

“I think the defense is getting better,” head coach Dick Vermeil said after Tuesday morning’s practice. “They were very disruptive today to everything the offense wanted to do. I was pleased with that.”

The he players who’ve been with Cunningham before believe their leader is up to the task.

“Gunther is a master motivator,” said defensive end Eric Hicks. “He takes a lot of responsibility on his shoulders. He thinks it’s all his fault when things go wrong. When in all reality, he did the best he can. We’re the ones out there running it.”