CONCORD, N.C. -- The blue and silver Chevrolet dipped to the bottom of the race track, and zoomed past the only vehicle in front of it with a move that carried a certain degree of finality. There are five races remaining in this Chase for the Sprint Cup, five trying events at five challenging tracks that can still shape the title picture. But in all reality, after Saturday night at Lowe's Motor Speedway, Jimmie Johnson's bid for an unprecedented fourth consecutive championship on NASCAR's premier circuit now comes down to a single afternoon.

For Johnson, it's effectively a one-race Chase. He'll deny it, of course, and point to a million possible doomsday scenarios, as any driver in his position would. But the 90-point lead he carried away from metro Charlotte on Saturday is the biggest any competitor has enjoyed at the halfway mark of the playoff series. Johnson is in a stronger position now than he's been in any of three most recent title runs. He's bound for his best track, tiny Martinsville Speedway, where he's won six of his last seven starts. Barring the kind of catastrophic mechanical failure that his No. 48 team has managed to avoid over its magical run, it all comes down to one final hurdle.

Talladega Superspeedway, Nov. 1. Because of the schedule switch prior to this season that helped facilitate the date swap between Atlanta and Auto Club Speedway, this year marks the first time that the menacing restrictor-plate venue has fallen this late in the Chase. Statistically it's one of Johnson's worse tracks, a place he's failed to finish six times, a place where chaos can erupt at any moment, a place where this past spring Carl Edwards went spinning into the restraining fence. If Johnson gets through 500 miles on that howling, sinister, metal-mashing Talladega surface with his car intact, then it's over.

Done.

Finished.

Naturally, Johnson doesn't agree.

"That's the track that you don't have any control at," he said of Talladega. "But at the same time, I mean, we're only halfway through this thing. So much can happen. Somebody at Martinsville can lose their brakes and clean you out. With the double-file restarts, there's going to be a lot of bumping and banging. Somebody can get into you and knock a valve stem out, or cut a tire. It's a nice point lead, but there's no need for anybody to get excited yet. We've got good tracks ahead for us, so from a team standpoint, we're excited. We're optimistic. But at the same time, there's a lot of danger out there, and we've got to be smart."

And yet, the evidence to the contrary is becoming overwhelming at this point. Consider that since the playoff format was implemented prior to the 2004 season, no driver before Johnson had ever won three of the first five Chase events. Consider that prior to Saturday night, the largest advantage enjoyed by a points leader leaving Charlotte was 69, held last year by you-know-who. Consider that with each passing season, Johnson asserts himself a little more, and wins the title by a wider margin. Yes, he rallied from the unthinkable sum of 146 points down at this point to win his first championship three years ago. But now, the only Chase driver with the potential to do that is the one in the lead.

Really, would anyone be shocked at this point if he left Martinsville -- where his average finish is 5.3, better than anywhere else on tour -- with another victory and a 150-point advantage? Would anyone be shocked if he became the first Chase champion to wrap this up at Phoenix, the penultimate event of the year? Chad Knaus preaches the danger of mechanical failure, as any good crew chief would. But when was the last time the No. 48 car wasn't running at the finish of a Chase race? Oct. 8, 2006.

At Talladega. And that was due to a crash -- Brian Vickers' now-infamous inadvertent spinout of his former teammate -- rather than a parts failure. Johnson has been knocked out by mechanical trouble exactly once in the past four years, a tribute to the unparalleled level of quality control at Hendrick Motorsports. Still, Knaus has his defenses up, as he should.

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We don't want to get ourselves too emotionally wrapped up in this thing, and have somebody come by and slap us in the face and take us out.

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JIMMIE JOHNSON

"That stuff does happen. It happens to everyone," Knaus said. "It's all about circumstances and timing. We're just fortunate that right now, and over the course of the last couple of years, we haven't had a significant failure in the Chase. But it's very, very possible. The potential is there every time you go on the race track."

But in this Chase, the No. 48 team is reaching the point where even a rare failure wouldn't necessarily be insurmountable. Leaving Charlotte, only three other drivers -- Mark Martin, Jeff Gordon, and Tony Stewart -- are within the window of 161 points, which is the most one driver can make up on another in a single race. And Gordon and Stewart, each more than 135 behind, are teetering on the edge. And Johnson hasn't finished outside the top nine at Martinsville since his first race there in 2002, when as a rookie he was knocked out by a vibration.

"I feel very good about racing for the championship," Johnson conceded. "If we don't have any problems, I feel we've got a very good chance to win the championship, racing for it. But the unknowns are what we can't control. That's why we don't want to get ourselves too emotionally wrapped up in this thing, and have somebody come by and slap us in the face and take us out. So we're just trying to keep our guard up."

For the teams still chasing Johnson, Talladega looms as something of a last stand.

"I told myself that if we're within about 75 or 100 points at Talladega, we'll decide how we're going to race," said Steve Letarte, Gordon's crew chief. "If we're outside of that, we're probably going to have to try to make something happen. I think if you're within 100, you just need to make sure you don't take yourself out. That's the whole thing about the Chase. You can't panic. These things aren't deciding who's winning the championship, they're just deciding who's losing it. Every week, we've got two more cars that are no longer involved."

This entire Chase has the feel of business as usual, as did Saturday night. With two of Johnson's closest pursuers, Martin and Juan Montoya, back in the pack after suffering damage in a chain-reaction restart incident, the No. 48 endured a rather stress-free night. Until Gordon made a late challenge on the final restart --one that ultimately proved futile when Johnson reassumed the point with 13 laps to go -- the team's most dramatic moments involved Johnson getting agitated over lap times, or Knaus' displeasure over the amount of quick-dry that crews dumped on the track.

It was a clinical, flawless effort of the kind Johnson and Knaus have become famous for, and it heightened the feeling of inevitability that's been circulating around this series for weeks. Still, Johnson stresses, 90 points can disappear in a heartbeat. When will the No. 48 team feel truly comfortable?

"Lap 287 at Homestead," said Knaus, referring to the final lap of the season. No surprise there. Even if a fourth championship is effectively sewn up in two weeks.

The opinions expressed are solely those of the writer.