Spaniard Marc Marquez won a fifth MotoGP title - his third in a row - then suffered a bizarre shoulder injury when celebrating victory in Japan.
Marquez, 25, dislocated his shoulder after enthusiastic hugs from his Honda team and British rider Scott Redding.
The victory gave Marquez his eighth win of the season at his team's home track.
"The shoulder just popped out. Luckily with the adrenalin it doesn't hurt, but I'll need to be careful not to overdo it on the dancefloor tonight," he said.
Redding said: "Once we were rivals, big rivals, now we have nothing but respect and fun. Sorry for the dislocated shoulder."
Ducati's Andrea Dovizioso was his main title rival but the Italian slid off while in second on the penultimate lap.
Fellow Honda rider Cal Crutchlow finished runner-up after Dovizioso's fall with Alex Rins (Suzuki) edging out Rossi (Yamaha) for third.
Marquez pulls a wheelie after crossing the finishing line
The MotoGP champion's shoulder needed treatment after being mobbed in the celebrations
But Marquez was not down for long - he was soon jumping on the podium
Marquez moves level with Mick Doohan on five titles in the top class, with only Valentino Rossi (7) and Giacomo Agostini (8) ahead of him.
"I feel really good. I worked really hard all weekend," said Marquez, who has won the title with three races to go.
"I was pushing really hard. I'm disappointed because Dovizioso deserved to be here on the podium."
Marquez started the race in Japan in sixth place and had never won a MotoGP race after failing to qualify in the top five places on the grid.
But he quickly passed Briton Cal Crutchlow and then moved in front of pole sitter Dovizioso to take the lead.
A mistake from Marquez allowed the Italian to go back in front before he again passed Dovizioso on lap 21 of 24 to move back into first place.
Dovizioso appeared to be lining up a passing manoeuvre on Marquez in the final laps but slid onto the grass from his rival's slipstream.
That allowed Crutchlow to claim second, with Alex Rins edging out Rossi to finish third.
1. Marc Marquez (Spa/Honda) 42mins 36.438secs
2. Cal Crutchlow (GB/LCR Honda) +1.573
3. Alex Rins (Spa/Suzuki) +1.720
4. Valentino Rossi (Ita/Yamaha) +6.413
5. Alvaro Bautista (Spa/Ducati) +6.919
6 Johann Zarco (Fra/Yamaha) +8.024
7 Maverick Vinales (Spa/Yamaha) +13.330
8 Dani Pedrosa (Spa/Honda) +15.582
9 Danilo Petrucci (Ita/Ducati) +20.584
10 Hafizh Syahrin (Mal/Yamaha) +24.985
1. Marc Marquez (Spa/Honda) 296 points
2. Andrea Dovizioso (Ita/Ducati) 194
3. Valentino Rossi (Ita/Yamaha) 185
4. Maverick Vinales (Spa/Yamaha) 155
5. Cal Crutchlow (GB/LCR Honda) 148
6. Johann Zarco (Fra/Yamaha Tech3) 133
7. Danilo Petrucci (Ita/Ducati Pramac) 133
8. Jorge Lorenzo (Spa/Ducati) 130
9. Alex Rins (Spa/Suzuki) 118
10. Andrea Iannone (Ita/Suzuki) 113