Kyle Busch became perhaps the most improbable NASCAR champion in history on Sunday, winning the Chase for the Sprint Cup finale at Homestead-Miami Speedway for the first title of his career.

Less than a year after a devastating crash that led to a broken leg and foot and seemingly ended any shot of qualifying for the post-season - let alone winning a title - Busch and his Joe Gibbs Racing crew led 41 laps and held off a late charge by Kevin Harvick, who finished 1.553 seconds behind in second place. 

Fellow Championship drivers Jeff Gordon and Martin Truex Jr. finished sixth and 12th respectively at the Ford EcoBoost 400.

All four drivers led at least three laps in the race, which was delayed about 95 minutes because of rain.

Busch's win capped an unlikely injury comeback from the February 21 crash that cost him 11 races.

NASCAR granted Busch a medical waiver, and he made the most of it with five wins - at one point winning four of five races - to crack the top 30 in the points standings and qualify for the post-season.

Gordon's attempt at a Sprint Cup championship in his 797th and final start of his career came up just short.

The 44-year-old driver led nine laps, but fell behind on a mid-race restart and never regained position.

Harvick, the defending champion, led 46 laps early on but spent most of the race behind Busch until making a late but fruitless attempt to pull ahead.

During green-flag pit stops on lap 140, Truex's car caught fire momentarily as sparks ignited when his crew was re-fuelling. Despite the incident, his car was not damaged. 

Truex jumped to the lead just past halfway after taking only two tires with just under 100 laps to go.

The gamble did not pay off as he quickly dropped to 12th just 20 laps later.

A major wreck early in the race knocked out fan favourite Dale Earnhardt Jr., Clint Bowyer, Aric Almirola, Casey Mears and others.

Bowyer made contact with Austin Dillon on lap 46 and spun, knocking Earnhardt's car into the wall.

Earnhardt, who won last week at Phoenix, hit the inside wall and came away with heavy damage to his car. He finished 40th.