Dani Pedrosa committed motor racing's most cardinal sin at Estoril on Sunday, when he took out world championship leading team-mate Nicky Hayden in a moment of madness that could cost the American the 2006 MotoGP crown.

Hayden started the penultimate event of the season with a 12-point lead over reigning five-times champion Valentino Rossi, who converted pole position into an early race lead - while his Camel Yamaha team-mate Colin Edwards dutifully held station in second.

By contrast, there was no such co-operation between Repsol Honda team-mates Pedrosa and Hayden - the cited reason being that fifth in the championship Pedrosa still had a slim mathematical chance of the title - but team orders is one thing, team destruction another.

Yet, exactly one lap after Hayden had squeezed inside Pedrosa for third, and with the 28 lap race less than seven-minutes old, the Spaniard - in a moment of utter madness - gambled Hayden and Honda's entire world championship lead on an inexcusably optimistic attempt to retake the position, which he later blamed on a braking mistake.

The 2006 rookie of the year - previously renowned for his cool head - appeared to forget who pays his wages as he tried to make the panicky pass stick but, as Hayden turned in to the left hander, Dani already had nowhere to go, lost his front wheel and wiped them both out.

Hayden, who has finished every other race this season, desperately tried to rejoin, but the damage to his RCV was too great and the furious American was left punching the ground amidst screams of anger and abuse directed at Dani... but most would probably have punched Pedrosa, whose fumbled pass was one of the most costly team-mate-on-team-mate mistakes ever seen in world championship motorcycle racing.

"I don't know what to say really - it just hurts," said a stunned Hayden. "Everybody's made a big deal about team orders, but I don't sign (Pedrosa's) cheques so I can't tell him what to do. I didn't expect Dani to pull over and let me by, but I definitely didn't expect him to do that.

"We should have had a plan in place - even when I passed Dani the first time he did not want to give the position to me," continued Hayden, his voice breaking. "I mean I had to get off the brakes just to get back by him. He had no orders - Honda didn't tell him not to race me hard - but I was watching Colin just following (Yamaha's) plan perfectly.

"I know it wasn't intentional. I just looked back when I was sliding on the ground and saw it was Dani. I didn't expect it from him - a guy that's won three world championships should know what it's like to fight for a title. I just couldn't believe it was Dani. That's not one of his moves.