One loose lug nut or flat tire, vowed Kenseth, would change the entire championship chase.

He was right, in a very big way.

Jeff Burton wipes his head as he talks to the media in the garage after his engine failed on lap 217 during the NASCAR Nextel Cup Subway 500 auto race at the Martinsville Speedway in Martinsville, Va., Sunday, Oct. 22, 2006. [AP]

An engine failure in Burton's car Sunday tightened the Chase for the championship standings, giving NASCAR the title hunt it coveted when it launched this format three seasons ago.

Kenseth is the new leader, leaving Martinsville Speedway with a faint 36-point margin over Kevin Harvick. It marks the first time the points leader has changed during the second half of the Chase.

Kurt Busch took over the top spot following the third Chase race in 2004 and never looked back, while Tony Stewart held down his lead for the final eight weeks of last season. Although both champions went into the finale capable of losing the title, neither did as the Chase failed to produce the dramatic buildup NASCAR coveted.

But this year is shaping up to be everything Brian France hoped and dreamed the Chase would be, with only 99 points separating Kenseth from eighth-place Kasey Kahne ¡ª an improvement over last year, when only four drivers were within 100 points of the leader at this stage.

This time around, everyone still has a chance. One bad pit stop or broken part can open it up for anyone to stake a claim on the title.

"It's anybody's championship," said Jimmie Johnson, who used a victory on Sunday to jump from seventh in the standings to third.

"Any team is still capable of winning the championship, the points are really close right now, so there can be a lot of moving and shaking and I don't think anybody is going to sleep well these next four races."

And that's all France ever wanted when he devised this system.

Scores of NASCAR traditionalists hate the Chase, complaining it's manufactured and contrived, and takes away from the model of consistency that was required to win the title every year before 2004.

Yes, the Chase does trample all over that tradition. But it's hard to argue that this way isn't a lot more fun.

When Kenseth won the title in 2003, the last year under the points system, NOBODY was still checking out the standings this late in the season. He ran away with that championship and no one could catch him from August on: He even clinched the title a week before the finale, meaning he could have gone fishing in the Florida Keys instead of racing at Homestead-Miami Speedway on that final Sunday.

Where's the drama in that? And why shouldn't NASCAR do something to prevent that from happening?

If the objective is to create interest that draws in fans, then NASCAR must maintain a way to keep people watching.

The Chase was the answer, and France correctly predicted that it would take a few seasons before it shaped into what he envisioned. Now NASCAR finally has a competitive playoff race, where it's absolutely impossible to guess who will hoist the trophy in Homestead next month.

But Kenseth isn't so sure this compelling season is a product of the system.

"Everyone thinks it's the most competitive one, but I kind of look at it the other way ¡ª it's the sloppiest Chase we've had so far. The least competitive one," he said. "Nobody has been able to run in the top 10 every week. No one is putting up staggering numbers, or that dominating streak we saw the first two years.

"With no trouble, Jeff Burton is probably the runaway winner of this thing. But, what we're seeing this year, is none of us are immune from trouble."

He's got a point. If Burton didn't get a flat tire three weeks ago in Talladega, he might have had a 100-point lead on the competition. He would have cushioned it with his third-place finish last week in Charlotte, giving him ample breathing room to afford his engine failure on Sunday.

Instead, his lead wasn't all that comfortable, and his 42nd-place finish was devastating: Burton dropped from first to fifth in the standings.

But interested observers will follow NASCAR to Atlanta this weekend to see if Burton can bounce back, if Kenseth can hang on, or if Johnson can mount another one of his furious comebacks.

Regardless of how the Chase got to this point, either because the system finally worked, or simply because Burton had a little bad luck, people are paying attention and have reason to change the channel during an NFL game, even if it's only for a brief update.

The Chase is far from perfect, and France is planning offseason tweaks in his continuing effort to get it right, but at least it has people talking.