Darlington, S.C. ? 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 reach of Nextel Cup points leader Kurt Busch with one race remaining.

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

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 managed a sixth-place finish and retained the points lead.

Gordon, a six-time Darlington winner, appeared on the way to an easy victory until he pitted on lap 337 during a 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.