Debutant Martin Vaculik was the shock winner of the Gorzow Grand Prix of Poland on Saturday.
The Slovakian ace replaced the injured Jarek Hampel after the Pole broke his leg in the last GP in Denmark.
And the 22-year-old made the most of his opportunity, setting a marker by winning his first heat.
He then posted three seconds and a heat win to make the semis, before coming second behind Tomasz Gollob in the second semi-final to reach the final.
In the main event of the evening, he led throughout to claim the spoils and become the sixth different GP winner in the six GPs so far this season.
Afterwards, he told Sky Sports: "Wow! I'm very happy - this was my first time in GP and I win the race.
"It is an amazing feeling, thank you all the fans. I wanted to try my best (in the final) and I won!"
Australian ace Chris Holder came second, while 17-year-old Polish debutant Bartosz Zmarzlik came third and compatriot Gollob brought up the rear.
As well as Vaculik, the other big winner on the night was current world champion Greg Hancock, who made the semi-finals to earn 12 points and increase his lead at the top of the standings from two to nine points.
The American veteran now has a total of 87 points, while Holder's second place saw the Australian move up to 78 points, level in the standings with compatriot Jason Crump - who failed to make the semis.
On a less positive note, British rider Chris 'Bomber' Harris, who had reached the final in Copenhagen last time, endured a miserable night, registering just one third place finish - and one point - to slip to 15th overall in the standings.