From second on the grid, Morbidelli grabbed the advantage on the opening lap, as Marquez, Luthi and poleman Mattia Pasini formed up in a tight group that would run together for the first part of the race.

Points leader Morbidelli was able to stay just clear of the battle for second between Marquez and Luthi, who made a number of attempts to pass at Turn 3 but consistently ran wide.

As Pasini faded, the order of the top three remained the same until the 18th lap of 25, when Marquez launched an attack on his Marc VDS stablemate Morbidelli at Turn 3 - only to himself run wide and surrender the position to Luthi.

The Swiss veteran tried to force his way by Morbidelli for the lead at the same corner the next lap, but couldn't get the move done, and fell back behind Marquez two laps later.

By now, Morbidelli had the margin out front he needed to win, the MotoGP-bound Italian crossing the line 1.312s ahead of second-placed man Marquez.

Luthi completed the podium in third after running wide with three laps to go, Morbidelli stretching his points lead to 26 with seven rounds left.

KTM's Miguel Oliveira had threatened to get among the leading group in the latter stages after charging up to fourth, but the Portuguese suffered a violent crash at Turn 8 with five laps left.

That left Francesco Bagnaia (Sky Racing VR46) to claim fourth, ahead of Pasini (Italtrans), Takaaki Nakagami (Team Asia) and the surviving Ajo-run KTM of reigning Moto3 champion Brad Binder.

Gresini's Jorge Navarro, Dominique Aegerter (Kiefer) and Hafiz Syahrin (Petronas) completed the top 10.

Fabio Quartararo (Pons) had qualified a commendable sixth, only to be taken out of the race at the very first turn by Xavi Vierge (Tech 3) in an incident that also removed Lorenzo Baldassarri (Forward) from contention. Issac Vinales (SAG) was also running inside the top 10 early on before crashing.

Danny Kent, standing in for Marcel Schrotter at Intact GP, didn't take the start after suffering a back injury in practice.

Race results:

Pos.	#	Rider	Bike	Time/Gap
1	21	Franco Morbidelli	Kalex	37'39.370
2	73	Alex Marquez	Kalex	1.312
3	12	Thomas Luthi	Kalex	2.544
4	42	Francesco Bagnaia	Kalex	3.070
5	54	Mattia Pasini	Kalex	3.745
6	30	Takaaki Nakagami	Kalex	8.827
7	41	Brad Binder	KTM	9.018
8	9	Jorge Navarro	Kalex	13.692
9	77	Dominique Aegerter	Suter	14.955
10	55	Hafizh Syahrin	Kalex	18.997
11	24	Simone Corsi	Speed Up	21.887
12	45	Tetsuta Nagashima	Kalex	22.028
13	49	Axel Pons	Kalex	23.008
14	57	Edgar Pons	Kalex	23.290
15	87	Remy Gardner	Tech 3	25.128
16	37	Augusto Fernandez	Speed Up	33.460
17	89	Khairul Idham Pawi	Kalex	33.931
18	2	Jesko Raffin	Kalex	40.110
19	20	Joe Roberts	Kalex	43.888
20	6	Tarran Mackenzie	Suter	46.097
21	27	Iker Lecuona	Kalex	2 laps
Ret	44	Miguel Oliveira	KTM	5 laps
Ret	62	Stefano Manzi	Kalex	12 laps
Ret	5	Andrea Locatelli	Kalex	13 laps
Ret	32	Isaac Viñales	Kalex	14 laps
Ret	97	Xavi Vierge	Tech 3	24 laps
Ret	19	Xavier Simeon	Kalex	24 laps
Ret	40	Fabio Quartararo	Kalex	-
Ret	11	Sandro Cortese	Suter	-
Ret	7	Lorenzo Baldassarri	Kalex	-
Ret	10	Luca Marini	Kalex	-