Tom Chilton wrapped up his first World Touring Car Championship victory at Sonoma after withstanding race-long pressure from Honda's Tiago Monteiro
The Briton took full advantage of his first series pole to lead from the start, while fellow front-row man and RML Chevrolet team-mate Yvan Muller lost out fighting for an inside line at Turn 2 and could not prevent Monteiro slipping by around the outside.
From there the duo began to ease away from the field, while Muller started to fall back into the clutches of the chasing Bamboo Chevrolets of Alex MacDowall and James Nash.
The top five ultimately stayed in that order for the remainder of the race, although Chilton had to withstand several attacks from Monteiro before he was finally able to stretch the gap past one second three laps from the end.
Muller was never in the hunt for victory, but was at least able to edge away from MacDowall and Nash to seal a lonely third.
Gabriele Tarquini had a similarly solitary drive to sixth, just under 15s down the road from Chilton.
It was far more frantic lower down the field, with defending champion Rob Huff bunching up a multi-car fight that grew to include Tom Coronel, Marc Basseng, Stefano D'Aste, Pepe Oriola and Tom Boardman, who had started from 20th position.
Coronel finally found a way past Huff's stubborn defence three laps from the end, and was able to pull a three-second gap by the flag.
Huff hung on to finish eighth ahead of Basseng, with D'Aste completing a trio covered by just 1.5s at the line.
Oriola beat Boardman to 11th by less than half a second.
Just behind them an eight-car battle raged for much of the race, with Lada's James Thompson able to defend 13th until the final laps, when Michel Nykjaer and Hugo Valente - both forced to start from the back of the grid - came through.
Results - 13 laps:Pos Driver Team/Car Time/Gap 1. Tom Chilton RML Chevrolet 23m24.716s 2. Tiago Monteiro Honda +2.161s 3. Yvan Muller RML Chevrolet +6.534s 4. Alex MacDowall Bamboo Chevrolet +10.659s 5. James Nash Bamboo Chevrolet +12.676s 6. Gabriele Tarquini Honda +14.897s 7. Tom Coronel ROAL BMW +18.530s 8. Rob Huff Munnich SEAT +21.561s 9. Marc Basseng Munnich SEAT +22.558s 10. Stefano D'Aste PB BMW +23.266s 11. Pepe Oriola Tuenti Chevrolet +26.219s 12. Tom Boardman Special Tuning SEAT +26.653s 13. Michel Nykjaer Nika Chevrolet +35.488s 14. Hugo Valente Campos SEAT +37.826s 15. James Thompson Lada +40.811s 16. Fernando Monje Campos SEAT +41.457s 17. Fredy Barth Wiechers BMW +41.469s 18. Charles Ng Engstler BMW +41.971s 19. Franz Engstler Engstler BMW +42.242s 20. Mehdi Bennani Proteam BMW +42.805s 21. Mikhail Kozlovskiy Lada +43.997s 22. Norbert Michelisz Zengo Honda +48.934s 23. Rene Munnich Munnich SEAT +1m08.203s Retirements: Darryl O'Young ROAL BMW 5 laps
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