Matt Neal took his first British Touring Car win of the season after a dramatic opening race at Knockhill in which title leader Colin Turkington failed to finish.
Neal's Honda Civic Tourer started on the soft Dunlop rubber and ran fifth early on.
Poleman Sam Tordoff's MG held the lead at the start from the soft tyre-shod Audi of Rob Austin, with Andrew Jordan and Gordon Shedden close behind.
Shedden dived by Jordan at the hairpin and moved forward to challenge Austin. Slight contact out of Clark's put the Audi off and dropped it briefly to fifth, promoting Shedden to second.
Jordan now came back at Shedden, passing the 2012 champion at Duffus Dip. But slight contact in the middle of the corner forced Shedden into a spin and the Honda estate hit Jordan off as it spun round.
That allowed Neal and Austin through. While Shedden was able to continue in fourth, Jordan retired with broken suspension.
Neal closed the gap to Tordoff and went ahead at Clark's just as the safety car was scrambled for the most significant clash of the race.
Turkington had started ninth after his grid penalty, but strong pace meant he was soon involved in a scrap for sixth with Jason Plato's MG and Mat Jackson's Motorbase Ford Focus.
Plato appeared to back the group up, allowing more and more cars to join the train as Turkington climbed over the back of the MG.
After several attempts, Turkington completed a move on Plato into Duffus Dip, but ran a little wide, meaning Plato and Jackson were both close to the BMW as the drivers reached Scotsman.
Plato turned in and tapped the BMW's rear, just as the MG was hit by Jackson. The MG and Ford continued, but Turkington was spat into the gravel, ending his race and bringing out the safety car.
Before the restart, Tordoff lost power and pulled off. He got going again, but the chance of a good result was gone.
Neal thus held Austin off to take the win once racing resumed, with Shedden completing the podium.
Jackson beat Plato for fourth, while Ciceley Mercedes driver Adam Morgan and the Speedworks Toyota Avensis of Tom Ingram came through to sixth and seventh despite starting 17th and 13th respectively.
Results - 27 laps Pos Driver Car Time/Gap 1. Matt Neal Honda 25m35.539s 2. Rob Austin RAR Audi +0.230s 3. Gordon Shedden Honda +2.049s 4. Mat Jackson Motorbase Ford +2.350s 5. Jason Plato MG +2.960s 6. Adam Morgan Ciceley Mercedes +3.829s 7. Tom Ingram Speedworks Toyota +7.328s 8. Aron Smith BMR VW +8.340s 9. Dave Newsham AmD Ford +9.231s 10. Nick Foster WSR BMW +9.269s 11. Alain Menu BMR VW +9.997s 12. Rob Collard WSR BMW +10.063s 13. Fabrizio Giovanardi Motorbase Ford +11.731s 14. Jack Goff BMR VW +11.997s 15. Warren Scott BMR VW +16.643s 16. Marc Hynes MG +20.132s 17. Martin Depper Eurotech Honda +20.363s 18. Jack Clarke Motorbase Ford +20.892s 19. Aiden Moffat Moffat Chevrolet +21.197s 20. Glynn Geddie UA Toyota +23.836s 21. Simon Belcher Handy Toyota +24.979s 22. Chris Stockton BTC Chevrolet +25.758s 23. Lea Wood Houseman Toyota +29.698s 24. Sam Tordoff MG +38.034s 25. Hunter Abbott RAR Audi +38.673s Retirements Ollie Jackson Welch Proton 22 laps Colin Turkington WSR BMW 17 laps Andrew Jordan Eurotech Honda 14 laps Robb Holland Rotek Audi 7 laps Daniel Welch Welch Proton 7 laps James Cole UA Toyota 4 laps