Victory for Rob Huff and a drive-through penalty for his RML Chevrolet team-mate Yvan Muller brought the World Touring Car Championship title race alive at Sonoma
Muller's penalty was awarded for tagging race leader Franz Engstler into a spin at the Carousel corner.
The incident proved costly for the triple world champion, who leaves the United States equal on 315 points with Huff at the head of the drivers' standings.
Engstler was the third BMW runner to pirouette out of first place. Reversed-grid poleman Stefano D'Aste spun on the opening lap after contact with Mehdi Bennani, promoting the Moroccan to the head of the field.
Bennani lasted just three laps out in front before losing control and making contact with the retaining wall.
Engstler was punted off on the following tour, moments before the safety car was called out to allow for Bennani's abandoned Proteam BMW to be removed from its dangerous position at Turn 9.
Huff could not escape the attentions of the chasing Norbert Michelisz, while Gabriele Tarquini sat a few car lengths back in third.
Michelisz was unable to stage a passing attempt, but hung on to Huff's bumper to finish 0.320 seconds back at the chequered flag.
"This is exactly what we have been working towards," said Huff. "Congratulations to Yvan, he drove a fantastic race in race one and I couldn't catch him, but I have to thank Norbert for driving such a clean race."
After power-steering problems in race one, Alain Menu had a trouble-free afternoon to work his way up from 10th on the grid to fourth.
Tom Coronel also made strong progress. Starting from 20th the Dutchman charged up the order, passing Tiago Monteiro for fifth on the last lap.
Results - 15 laps:Pos Driver Team/Car Time/Gap 1. Rob Huff Chevrolet 29m19.176s 2. Norbert Michelisz Zengo BMW + 0.320s 3. Gabriele Tarquini Lukoil SEAT + 1.199s 4. Alain Menu Chevrolet + 3.718s 5. Tom Coronel ROAL BMW + 7.571s 6. Tiago Monteiro Tuenti SEAT + 8.207s 7. Alex MacDowall Bamboo Chevrolet + 12.682s 8. Tom Boardman Special Tuning SEAT + 13.847s 9. Stefano D'Aste Wiechers BMW + 14.220s 10. Franz Engstler Engstler BMW + 15.643s 11. Pepe Oriola Tuenti SEAT + 18.811s 12. Darryl O'Young Special Tuning SEAT + 21.656s 13. Alberto Cerqui ROAL BMW + 21.997s 14. Yvan Muller Chevrolet + 23.467s 15. Tom Chilton Arena Ford + 24.319s 16. Robb Holland Bamboo Chevrolet + 25.184s 17. James Nash Arena Ford + 30.630s 18. Aleksei Dudukalo Lukoil SEAT + 41.557s Retirements: Mehdi Bennani Proteam BMW 3 laps Fernando Monje SUNRED SEAT 1 lap
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