UPDATE 2: "Unfortunately it looks like they [Marquez and Pedrosa] slightly touched each other and the rear wheel speed sensor [on Pedrosa's bike] was broken.
"After that there was no more traction control, which is why Dani crashed" - Livio Suppo, Repsol Honda team manager to Dorna TV.
Suppo was seen having a lengthy conversation with race winner Marc Marquez in parc ferme, presumably explaining what had happened.
"I touched Pedrosa a little bit and I saw that he crashed," Marquez confirmed.
UPDATE 1: Dani Pedrosa 'cleared of serious injury'.
Jorge Lorenzo has been handed an early two-second lead in today's Aragon MotoGP race after drama for Honda team-mates and title rivals Dani Pedrosa
and Marc Marquez.
The trio - Lorenzo, Pedrosa and Marquez - were running nose-to-tail on lap 6 of 23 when Marquez swerved to avoid second-place Pedrosa's rear wheel under braking for Turn 12, running wide before rejoining the circuit.
Moments later, Pedrosa highsided on the exit of the same left-hander.
It is not clear if there was light contact between the team-mates but the fall may well have cost Pedrosa, celebrating his 28th birthday today, any chance of the 2013 title.
Rookie Marquez held a 34-point lead over both Lorenzo and Pedrosa heading into the race.
Pedrosa, who broke his collarbone earlier this year, is being checked in the Medical Centre for a 'suspected left knee injury'.Marquez caught and passed Lorenzo to win the race, building his title lead to 39 points. Pedrosa is now 59 points adrift with only 100 still available.