Rob Huff was the beneficiary of a controversial clash between his RML Chevrolet team-mates as he won the second World Touring Car Championship race at Shanghai.
Race one victor Alain Menu had appeared well-placed to do the double after working his way around the outside of poleman Tom Coronel at the hairpin on lap five.
Reigning WTCC champion Muller also passed Coronel on the inside of the corner, as the factory Chevrolet men progressed from their reverse-grid start slots towards their familiar formation at the front of the field.
The flashpoint came three laps later, when Muller made an aborted overtaking attempt into Turn 1 and rammed Menu out of the lead.
Despite Muller's best efforts to back out of the manoeuvre, Menu was knocked backwards off the track and wrecked his tyres regaining control.
The clash paved a clear path for Huff into the lead. He was delighted with his dramatic turn of fortune after suffering major wheelspin away from the standing start.
After qualifying fourth at the beginning of the weekend, I could never have believed this could have happened," said Huff, who has extended a sudden lead in the drivers' standings.
"I had a clutch problem at the start and found myself behind Yvan, but I was quite happy to stay there.
"This is not the way we wanted to win, but I will take it as it comes."
Perhaps to avert a drive-through, Muller handed second place back to Menu on lap 10. But having appeared the fastest factory Chevrolet driver throughout the Shanghai meeting, Menu's ruined tyres meant he was unable to maintain the position and dropped to third two laps from home.
"It is too early to speak about the incident, but I think that has probably cost both [Yvan] and myself the championship," said an emotional Menu, referring to an ongoing investigation into the incident by race officials.
With just the Macau finale remaining, Huff now leads the standings on 390 points, provisionally 23 ahead of Muller, with Menu 38 points adrift on 352.
Coronel held off Independents' victor Stefano D'Aste for fourth place. Wiechers-Sport racer D'Aste was forced to contend with a flapping left-front door for much of the race, but was rewarded by making large inroads in the Yokohama Independents' Trophy title race.
Norbert Michelisz, class points leader entering the weekend, was swiped by Alex MacDowall at Turn 1, delaying the Bamboo racer and forcing Hungarian Michelisz into retirement. Independent championship challenger Pepe Oriola also failed to finish.
Mehdi Bennani took a fine sixth place for Proteam, ahead of Gabriele Tarquini - who lost ground in the early laps.
By far the most intense battle of the race was a seven-car fight over eighth place, led for a lengthy period by a defensive Tom Boardman.
The Special Tuning racer was eventually passed on the grass at Turn 3 by Colin Turkington on the last lap.
Results - 13 laps: Pos Driver Team/Car Time/Gap 1. Rob Huff Chevrolet 25m17.714s 2. Yvan Muller Chevrolet + 1.195s 3. Alain Menu Chevrolet + 2.698s 4. Tom Coronel ROAL BMW + 4.378s 5. Stefano d'Aste Wiechers BMW + 4.866s 6. Mehdi Bennani Proteam BMW + 5.574s 7. Gabriele Tarquini Lukoil SEAT + 20.406s 8. Colin Turkington WSR Chevrolet + 25.189s 9. Tom Boardman Special Tuning SEAT + 26.741s 10. Alberto Cerqui ROAL BMW + 27.167s 11. Tiago Monteiro Honda + 27.342s 12. Aleksei Dudukalo Lukoil SEAT + 28.113s 13. Darryl O'Young Bamboo Chevrolet + 30.937s 14. Fredy Barth SUNRED SEAT + 32.626s 15. Franz Engstler Engstler BMW + 35.170s 16. Fernando Monje SUNRED SEAT + 35.249s 17. Alex MacDowall Bamboo Chevrolet + 35.368s 18. Hugo Valente SUNRED SEAT + 41.675s 19. Tom Chilton Arena Ford + 42.220s 20. Eric Kwong Look Fong Chevrolet + 1m15.910s 21. Filipe Souza China Dragon Chevrolet + 1m21.126s 22. Ng Kin Veng China Dragon Chevrolet + 1m34.329s 23. Charles Ng Engstler BMW + 1 lap 24. Norbert Michelisz Zengo BMW + 1 lap Retirements: Alex Liu Engstler BMW 11 laps Kelvin Leong Song Veng Honda 7 laps Pepe Oriola Tuenti SEAT 6 laps James Nash Arena Ford 0 laps