CONCORD, N.C. -- Jimmie Johnson can't believe how he got here. His competitors wonder if they ever will.

Forget Kyle Busch and his eight wins, the sport's top driver is its reigning champion. Johnson's history of momentous stretch runs in the Chase for the Sprint Cup makes his 72-point lead on Carl Edwards seem much larger.

That makes tonight's Bank of America 500 at Lowe's Motor Speedway a pivotal one for those trying to keep close to Johnson. Give up more points to Johnson and it wouldn't be outlandish to anoint him champion for a third consecutive season -- even with five races left.

How Johnson got to this point befuddles him.

"I have thought my career was over at many different levels from the off-road [truck] ranks and Chevrolet pulling out of the series I was racing in," Johnson said. "At times, I was a slow learner who made a lot of mistakes. Through the off-road ranks, I tore up so much."

He preserved, won races and off-road racing titles and moved to ASA, a short-track stock car series. He later joined his owners in going to the Busch Series where he won one race and turned a personal meeting with Jeff Gordon into what would become one of NASCAR's premiere rides.

He sought Gordon's advice about possible Cup rides he was considering unaware that Gordon and Rick Hendrick plotted adding another team to Hendrick Motorsports. Gordon and Hendrick later tabbed Johnson as their driver.

"My whole life I have worked really hard and have been OK," Johnson said.

"I have always wondered why I didn't have my chance and why everything didn't work out in the ASA or the Busch Series or in Trucks.

"Now that it is all said and done, I look back on it, I get it. It wasn't my turn yet. Now it's my time and thank God it's this massive scale."

It's hard to imagine anyone topping Johnson based on how he's run the final six races the past two years.

He has finished first or second nine times in those 12 races and not finished worse than 14th in any of those races.

Three of the four years of the Chase, no one has scored more points in the final six races than Johnson.

Johnson showed no sign on letting up Friday night, posting the fastest lap in the final practice session.

Biffle, who trails Johnson by 77 points, admits this it Johnson's title to lose.

"That's clear," Biffle said, aware of Johnson's late-season success.

Carl Edwards disagrees.

"I don't think we're far enough back yet, but we didn't help ourselves by letting him get that many points on us last week," he said.

Johnson gained 62 points on Edwards after last weekend's race at Talladega when Johnson finished ninth and Edwards placed 29th after starting a late-race crash.

Making it tougher on Edwards and others is that Lowe's Motor Speedway and Martinsville Speedway, where the series races next week, are among Johnson's best tracks.

Johnson has won the fall race at Lowe's two of the last four years and won the fall Martinsville race three of the last four years.

"There's no question that they've been consistently better at these next two race tracks then the rest of the field," said Jeff Burton, who trails Johnson by 99 points entering tonight's race. "What we have to do is do it better. They have set a standard at these two race tracks that are very difficult to overcome but we just have to do it.

"We're not going to give it to him. They're going to have to go earn it. We can't ask them nicely to give it to us, we just have got to go take it from them."

No one has done the past two years.