Jimmie Johnson has fought through mistakes, mechanical failures and the despair of losing friends in a plane crash to charge back into NASCAR's closest championship battle ever.

He got some unexpected help Sunday from teammate Jeff Gordon, whose crew made an uncharacteristic mistake on pit lane. Johnson took advantage of the opportunity to win the final Southern 500 at Darlington Raceway and move within easy reach of Nextel Cup points leader Kurt Busch with one race remaining.

Johnson dominated most of the 26-race regular season, but lost a big lead when his No. 48 Chevrolet team started to experiment with new parts. He then started the new 10-man, 10-race playoff-style championship poorly, falling to ninth place, 247 points behind leader Busch after the first four races of the Chase for the Cup.

But four victories in the last five races, combined with a sixth-place finish last week at Phoenix, have given the third-year Cup driver momentum going into next Sunday's finale at Homestead-Miami Speedway.

"I can't believe it," said Johnson, who has dedicated his season to the 10 people killed in the crash Oct. 24 of a team plane. "Fighting our way back in this championship with what took place with the airplane and Hendrick Motorsports, I just can't believe it.

"We have eight wins now in the season with everyone still healing from the loss over everybody on that airplane. That void inside of me just isn't filled, but this certainly helps. This is good medicine. We'll just keep rolling with it."

Busch fought an ill-handling car after his Ford was damaged early in the race when rookie Brendan Gaughan bounced off the wall and hit him. Busch somehow overcame adversity, as he has several times during the Chase, to post a sixth-place finish and retain the points lead. "We feel like we dodged a bullet today," Busch said. "We can smile about the way it finished, but we didn't race very well. It was an evil racecar. But the kind of effort my team put in on pit road today is what is the key to winning a championship."

Johnson, who gave his crew credit for getting him to the lead late in the race with two fast pit stops, had to overtake rookie Kasey Kahne and Jamie McMurray after they stayed out when the other leaders pitted for tires during the last of eight caution periods.

The race restarted with 18 to go in the 367-lap event and Johnson, in third, passed Kahne for second place on Lap 352 and took the lead from McMurray on Lap 359. Then he pulled away to his 14th career win.

"Those guys were racing real hard," Johnson said. "I knew I had to get everything I could on my new tires. I got by the number nine [Kahne] and then ran down the number 42 [McMurray].

"He was doing a good job of trying to put his car where I wanted to be and I got into him a little bit off Turn Four and loosened him up. Then I finally set him up so I could get inside of him. It was just good hard racing."

Johnson, who beat Mark Martin to the finish line by 0.959 of a second -- about six car lengths -- also won the race in March on Darlington's tough 1.366-mile oval. Gordon led a race-high 155 laps. Johnson led 124.

Gordon, a six-time Darlington winner, appeared on the way to an easy victory, dominating the second half of the race until he pitted on Lap 337 during another caution period. His car came down on an air hose, costing him precious time and the four-time series champion, leading coming entering pit road, came out sixth.

He charged to the end but couldn't catch Johnson or Martin. McMurray finished fourth, followed by Kahne, Busch and rookie Carl Edwards.

"If we're going to win this championship, we can't make these kind of mistakes," Gordon said.

Heading to the finale, Busch, who came into Sunday's race leading Gordon by 41 points, now leads Johnson by 18 and Gordon by 21. Dale Earnhardt Jr., who had to pit late in the race to change a battery, finished 11th and now trails by 72 points, with Martin 82 behind.