Stefan Bradl took his first Moto2 victory in an astonishing Estoril race, which was led by debutant Kenan Sofuoglu for much of the distance.
The incredible event also saw long-time midfielder Alex Baldolini score his maiden podium after nine years at world championship level, champion Toni Elias retire for the first time all year, and Andrea Iannone look set to come from 34th on the grid to victory before crashing.
World Supersport champion Sofuoglu had taken the late Shoya Tomizawa's seat at Technomag-CIP for the last two races, but the weather in Portugal meant he had only tried the Moto2 Suter in the wet prior to the race, which took place on a dry track with just a few damp areas remaining.
Despite his huge experience deficit, Sofuoglu briefly snatched the lead at the start, before polesitter Gabor Talmacsi repassed him into Turn 3. That sent Sufuoglu wide and momentarily down to fourth, but he immediately fought back and at the end of lap two he swept from third to first in a three-abreast move with Talmacsi and Yonny Hernandez on the main straight.
After a quick exchange with Hernandez - whose time at the front ended when he fell at Turn 1 on lap five - Sufuoglu broke clear and charged away into a seven-second lead.
Bradl (Viessmann Kiefer Suter) and the surprising Baldolini (Caretta ICP) started hunting Sufuoglu down once they had passed the fading Talmacsi on lap 11. The pair took a second per lap out of Sufuoglu's lead, breezing past on the main straight on lap 19 of 26.
By that time, Speed Up rider Iannone was into an astounding fourth place. From 34th on the grid he had made a conservative start, before beginning to tear through the field - sometimes 2-3sec per lap quicker than anyone else. But just as he got the leaders within his sights, he fell at Turn 1.
That left Bradl and Baldolini free to fight it out, with Baldolini twice sneaking ahead but quickly repassed on both occasions as Bradl held on to win by 0.088s.
Behind them, a nine-bike tussle developed over third place, finally won by Alex de Angelis, who edged out Scott Redding (flying through from 25th on the grid) by a scant 0.012s at the line.
Sufuoglu followed them in fifth, with Raffaele de Rosa, the charging Anthony West, Talmacsi, long-time third-place man Dominique Aegerter, Karel Abraham and Hector Faubel also within 1.7s of the podium.
Julian Simon could only finish 12th, but still looks good for second in the championship as Iannone was 21st after his crash.
Elias was having a quiet race in the lower part of the top 10 when he crashed at Turn 1. He rejoined for a few laps before parking in the pits.
Carmelo Morales made his first appearance since his horrific Catalunya crash and held fifth for a while before falling. He recovered to 20th.
Pos Rider Bike Time/Gap
1. Stefan Bradl Suter 46m59.723s
2. Alex Baldolini ICP + 0.068s
3. Alex de Angelis Motobi + 2.830s
4. Scott Redding Suter + 2.842s
5. Kenan Sofuoglu Suter + 2.947s
6. Raffaele de Rosa Tech 3 + 3.311s
7. Anthony West MZ + 3.385s
8. Gabor Talmacsi Speed Up + 3.952s
9. Dominique Aegerter Suter + 4.284s
10. Karel Abraham FTR + 4.311s
11. Hector Faubel Suter + 4.492s
12. Julian Simon Suter + 13.006s
13. Axel Pons Pons Kalex + 26.529s
14. Simone Corsi Motobi + 27.760s
15. Robertino Pietri Suter + 28.259s
16. Thomas Luthi Moriwaki + 28.311s
17. Jules Cluzel Suter + 28.333s
18. Yonny Hernandez BQR + 37.873s
19. Claudio Corti Suter + 38.092s
20. Carmelo Morales Suter + 38.227s
21. Andrea Iannone Speed Up + 46.976s
22. Sergio Gadea Pons Kalex + 1m01.779s
23. Xavier Simeon Moriwaki + 1m25.872s
24. Fonsi Nieto Moriwaki + 1m26.029s
25. Vladimir Ivanov Moriwaki + 1m51.690s
26. Yuki Takahashi Tech 3 + 1 lap
27. Ferruccio Lamborghini Moriwaki + 1 lap
28. Yannick Guerra Moriwaki + 1 lap
29. Mashel Al Naimi BQR + 1 lap
Ricard Cardus Bimota 23 laps
Roberto Rolfo Suter 22 laps
Dani Rivas BQR 19 laps
Toni Elias Moriwaki 17 laps
Ratthapark Wilairot Bimota 14 laps
Valentin Debise ADV 13 laps
Kenny Noyes Promoharris 13 laps
Michael Ranseder Suter 5 laps