Marc Marquez strengthened his grip on the MotoGP world title as the championship rookie battled to his sixth win of the season at Aragon.
The Repsol Honda rider wrapped up victory on home territory over Yamaha's Jorge Lorenzo, extending his advantage to 39 points over the reigning world champion.
However the victory wasn't without controversy, with Dani Pedrosa highsiding out of second place as a result of sensor damage after light contact from team-mate Marquez early in the race.
Pedrosa is now 59 points adrift in the title race with four rounds remaining.
In Pedrosa's absence, Valentino Rossi returned to the rostrum with a tenacious ride to third, the Italian emerging on top of a multi-rider battle with Alvaro Bautista, Stefan Bradl and Cal Crutchlow.
Record-breaking rookie Marquez is now on course to become the first ever premier class newcomer to clinch the championship since American legend Kenny Roberts achieved the feat in 1978.
Lorenzo made a storming start to the race, grabbing the lead into the first corner from second place on the grid.
The Factory Yamaha rider displayed a blistering turn of pace to immediately make a break in the first few corners, opening a gap of 0.8 seconds by the end of the opening lap over Marquez, who moved into second place after a pass on Pedrosa.
Rossi was lying in fourth position ahead of LCR Honda's Stefan Bradl and Cal Crutchlow on the Yamaha Tech 3 M1.
PBM rider Michael Laverty, riding the ART machine for the first time at Aragon, slid off on the opening lap in an incident involving Luca Scassa and Danilo Petrucci on the Ioda-Suter.
Scassa, making his MotoGP debut on the Cardion AB ART as a replacement for Karel Abraham, was able to re-join the race and crossed the line 17th of the 19 finishers.
Lorenzo continued to set the pace but his lead was being gradually reduced by Marquez and Pedrosa as Rossi dropped off the pace of the top three.
Pedrosa put a move on Marquez on the brakes at Turn 7 on the fourth lap and set his sights on pulling in the race leader.