Moment of the race was when Marc Marquez overtook Valentino Rossi around the outside at the top of the Corkscrew, on lap 4 of 32.
The rookie held on as he ran over the kerb and onto the gravel during the downhill plunge - almost a carbon copy of Rossi's 2008 pass on Casey Stoner.
Marquez then reeled in pole sitter Stefan Bradl and took the lead from the German shortly after the halfway mark.
Title contenders Dani Pedrosa and Jorge Lorenzo were returning from collarbone injuries at last weekend's German round.
Andrea Iannone was ruled out after dislocating his shoulder and is not replaced. Iannone's long-injured team-mate Ben Spies was replaced by Moto2 rider Alex de Angelis.
American Blake Young was due to make his second wild-card appearance of the year with Attack Performance Racing, but withdrew after heavy damage to the bike on Friday.
for pictures from the grand prix...
1. Marc Marquez
ESP Repsol Honda Team (RC213V) 44m 0.695s
2. Stefan Bradl
GER LCR Honda MotoGP (RC213V) 44m 2.993s
3. Valentino Rossi
ITA Yamaha Factory Racing (YZR-M1) 44m 5.193s
4. Alvaro Bautista
ESP Go&Fun Honda Gresini (RC213V) 44m 5.252s
5. Dani Pedrosa
ESP Repsol Honda Team (RC213V) 44m 9.952s
6. Jorge Lorenzo
ESP Yamaha Factory Racing (YZR-M1) 44m 13.665s
7. Cal Crutchlow
GBR Monster Yamaha Tech 3 (YZR-M1) 44m 15.999s
8. Nicky Hayden
USA Ducati Team (GP13) 44m 34.658s
9. Andrea Dovizioso
ITA Ducati Team (GP13) 44m 34.824s
10. Hector Barbera
ESP Avintia Blusens (FTR-Kawasaki CRT)* 45m 3.064s
11. Alex De Angelis
RSM Ignite Pramac Racing (GP13) 45m 3.299s
12. Colin Edwards
USA NGM Forward Racing (FTR-Kawasaki CRT)* 45m 4.288s
13. Danilo Petrucci
ITA Came IodaRacing Project (Suter-BMW CRT)* 45m 21.145s
14. Karel Abraham
CZE Cardion AB Motoracing (ART CRT) +1 lap
15. Yonny Hernandez
COL Paul Bird Motorsport (ART CRT) +1 lap
16. Hiroshi Aoyama
JPN Avintia Blusens (FTR-Kawasaki CRT)* +1 lap
17. Bryan Staring
AUS Go&Fun Honda Gresini (FTR-Honda CRT) +l lap
18. Lukas Pesek
CZE Came IodaRacing Project (Suter-BMW CRT)* +1 lap
GBR Monster Yamaha Tech 3 (YZR-M1) DNF
ESP Power Electronics Aspar (ART CRT) DNF
Randy De Puniet
FRA Power Electronics Aspar (ART CRT) DNF
ITA NGM Forward Racing (FTR-Kawasaki CRT)* DNF
GBR Paul Bird Motorsport (PBM-ART CRT)* DNF