Torrential rain greets the grid in the middle of the ITV Sport interviews, the race was delayed to the surprise of nobody trackside.
Ronan Pearson will lead the drivers away under safety car conditions.
After five laps behind the safety car, Ronan Pearson accelerates away from the pack and starts the third race of the day followed swiftly by Ricky Collard and Dan Lloyd
Tom Ingram immediately dives down the inside of Andrew Watson for fourth.
Josh Cook and Jake Hill fight side by side out of the final corner on lap five, with Hill just keeping the Honda of Cook behind him.
Whilst Cook and Hill fight, Sutton pulls a big gap further up the road.
Collard and Lloyd come together multiple times into the first corner sending Collard sideways across the grass and he just about manages to keep control of his Toyota to stay in the fight for second.
Lloyd moves up to second in the CUPRA, chasing down the rookie Pearson in the Excelr8 Hyundai.
Nick Halstead goes straight on in the other Hyundai at the hairpin, bringing out the safety car.
Racing resumes on lap eleven of twenty seven, Pearson gets a great start again and leaves Lloyd for dead and battling with Ash Sutton for second place.
Jake Hill goes piling into the back of his WSR teammate Stephan Jelley at the hairpin, sinning Jelley and sending Hill right down the order after a great first two races.
Rob Huff and Daryl DeLeon for Team HARD. Racing both retire with mechanical and electrical issues respectively.
Sutton breezes past Lloyd and Pearson for the lead and the Napa Ford starts to build the lead gap that BTCC fans are becoming accustomed to this season.
Jake Hill goes wide and lets seven cars through at the final hairpin, contact with his other teammate Coin Turkington only slows himself down further.
Cook passes Pearson with relative ease as the Honda goes Ford Focus hunting for the lead.
Lloyd and Ingram come together after Ingram misjudges the breaking for the final hairpin, Lloyd catches the sin perfectly and pulls away from Ingram slightly coming over the start line.
Ingram clears Lloyd on lap twenty two at turn one
Micheal Crees finds the grass at turn three thanks to contact with Jelley, but manages to re-join with no drama.
Dexter Patterson in the Team HARD CUPRA is up to seventh, a potential best finish of the season for the local driver.
Lloyd is battling with Collard and gets forced down the order, Aiden Moffat wants to have a go at the struggling Lloyd coming onto lap twenty three.
Sutton is clear up front with a dominant six second gap to Cook in second.
Penultimate lap, Collard remains fifth and both Hyundai drivers fight for the final podium spot. Pearson defends for his life from the defending champion Ingram, but his fight is no match for the aggressive attacks of his teammate.
Sutton comes home to win for Napa Racing UK, with Josh Cook in second and Tom Ingram stealing the final podium position away from his rookie teammate and pole sitter Ronan Pearson.
Sutton walks away from Knockhill with a healthy thirty-nine point lead over Tom Ingram and Jake Hill.