Craig Cook blasted round Richard Lawson on the last bend of the Peugeot International Speedway Championship to claim the title at the death.
The Edinburgh No 1, representing Great Britain, was last out the gate in a mouth-watering final that also included Aussies Aaron Summers and Josh Grajczonek.
It was GB rival and Glasgow No 5 Lawson who made the gate and although Cook fought into second, the home rider blocked his runs around the inside.
But Cook switched his focus to the outside on the final bends – and sensationally powered round Lawson to take victory on the line.
It brought a bumper crowd to their feet – despite the rivalry between the Scottish clubs.
Cook admitted he’d almost killed his own chances after picking the poorer gate in the final – but sold the man in front a dummy to get by him.
The British Grand Prix wild card said: “I don’t know what I was thinking – you don’t let Richard Lawson off the inside of you – not with a good gate like gate two. He just popped out and went.
“It made it a bit more interesting for the fans and gave them something to watch. It probably wasn’t great for the Glasgow fans but it was great racing nevertheless.
“Richard looked at me and saw how quick I was round the inside of turn one and two of the second lap. He saw what I was doing there – I sold him a dummy and went to go round the inside after that. But I knew what I had to do and I knew what he was going to do.
“I needed to carry as much momentum as possible so on the back straight, I just sat back and got the bike driving. He nipped back and went to the kerb because I think he was scared that I was going to cut back up the inside of him.
“He just allowed me a big gap into turn three, to let me get some momentum into the turn, and fortunately I carried enough around just to nip past him on the line.”
Lawson conceded that Cook had ridden an intelligent race.
He said: “I probably rode a bit too defensively. He had come under me on the lap before and I went there. He sold me the dummy and got round me on that last bend.
“But credit to him – it was a good race. I just didn’t quite have enough but sometimes it goes that way.
“It was either go really, really wide and leave myself vulnerable – or go tight and leave myself open to letting him round. It’s a catch 22, but it is what it is and it was a good meeting.”
The final aside, the race of the day came in heat 11 when Glasgow captain Summers produced a similar move on Edinburgh’s Justin Sedgmen and raised the roof.
Sedgmen made the semi-final along with Jonas B Andersen, Summers and Grajczonek but it was the latter two who made it through.
Cook made the final with a flawless 15-point maximum, Lawson joining him there automatically.
Elsewhere there were positive showings from Plymouth’s Jack Holder and Somerset’s Richie Worrall, who both scored nine – while home trio James Sarjeant, Hynek Stichauer and Nick Morris bagged eight, five and eight respectively.