Alcaniz, Spain (AFP) - Italy's Franco Morbidelli extended his Moto2 world championship lead by winning Sunday's Aragon Grand Prix as his title rivals faltered.

Morbidelli led compatriot Mattia Pasini and Portugal's Miguel Oliveira to extend his lead to 21 points over Switzerland's Thomas Luthi, who finished fourth, with just four races to go.

Alex Marquez, younger brother of three-time MotoGP champion Marc Marquez, crashed out after 10 laps, realistically ending his fight for the championship as he slipped behind Oliveira into fourth in the standings.

Valentino Rossi, making a remarkable comeback after a three-week layoff due to a broken leg, finished in fifth.