Dani Pedrosa escaped serious injury in a big highside, triggered by contact with team-mate Marc Marquez in Sunday's Aragn MotoGP.
But Pedrosa's title hopes look to have suffered terminal damage, slipping 59-points from Marquez with just four rounds remaining.
Pedrosa and Marquez were running second and third behind Jorge Lorenzo when Marquez missed his braking point on lap 6 of the race.
The rookie tried to avoid Pedrosa, but made light contact - snapping a cable and disabling Pedrosa's traction control, causing Pedrosa to highside on the exit of the turn.
CLICK HERE for more pictures of the incident.
Afterwards, Pedrosa was sent to the Medical Centre for checks. Sunday was Pedrosa's 28th birthday.
"Fortunately I'm fine physically," said Pedrosa. "I took a heavy knock to my hip and my groin area, but I was able to escape relatively unhurt from what was a big crash.
"Marc went in too wide on the corner entry, clipped me from the outside and I went flying when I got on the gas. My mechanics told me later that the traction control cable had been cut by the contact."
The Marquez-Pedrosa incident is currently under investigation by Race Direction. Pedrosa told the official MotoGP website: "Whatever the decision I will still have zero points."
"They were braking in a different way, different style for that corner," added team manager Livio Suppo. "Marc is not stupid. He knows a touch could mean a big problem also for him. He didn't do it deliberately. Unfortunately these kind of things can happen. Dani is in pain, but more than that it is a big disappointment. I totally understand."
Marquez went on to win the race from Lorenzo, who is now 39 points behind the reigning Moto2 champion.
Honda will no doubt protect the sensor cable in future, but it is nonetheless surprising that the traction control system didn't revert to a safe/back-up mode once the sensor had failed.