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.

"I know Dani was still mathematically in with a shot of the title before the race, but I'm a team player and if it was the other way around I wouldn't have been leaning on him and I wouldn't have been stuffing him. Not for a world championship. Not my team-mate. But like I said Honda didn't tell him. The guy didn't have any team orders and he's paid to race hard. I don't expect guys to pull over for me but we should have had a plan. Come on! 15 races down, a world title on the line, seven other Hondas. It was pretty clear Colin was doing all he could for Rossi. You think he was going to pass Rossi?

"Everybody at Repsol Honda is feeling just as sick as I am. I hate it for myself, for the team, for Dani. You work your whole life for something and to be this close, then have it slip away from you, is tough. I'm not going to just brush it off - it could have cost me the world championship. That's something I'll have to live with for the rest of my life. We're professionals and Dani did come to my motorhome afterwards and we shook hands. I'm sure he hates it and it makes him look terrible. I know he's got to feel bad."

"What can I say? I made a mistake and I'm really sorry," offered Pedrosa. "It's the first time I've hit another rider in my career - it's never happened before in practice or racing in six years and it's happened at the worst moment that I could do it. Obviously I'm very unhappy and Nicky is not happy and I just want to apologise because I made a mistake. I said sorry to Nicky and I can understand that he is very upset - I wish I could change it. I didn't want to pass him at that moment. I braked and my rear wheel came off the ground and then it touched the ground again, I got a little more speed. I couldn't stop the bike and there was nowhere to go. I have a fracture in my little finger but we have time for it to be ok for Valencia."

The only 'good' news for Hayden, Pedrosa and Honda is that Toni Elias deprived Rossi of the full 25 points on offer at Estoril - meaning that the Italian will take an eight, instead of 13-point, championship lead into the Valencia showdown in two week's time.

That is still enough to allow Rossi to finish second and take the title, but if Hayden wins with another rider - such as Pedrosa - third, then Nicky and Honda could sensationally snatch the crown.

"I've proved this weekend that I wasn't going to give up without a fight and even now I believe I'm pretty strong," insisted Nicky. "This was not one of my best tracks and I've come here and gone quick - I was fastest in one session, got on the front row and had a good race pace. I need Dani's help now because anything could happen in Valencia, so I hope they don't suspend him and that his hand's ok. I don't know if I'll forgive him, but I told him there's one way to make it up to me and that's if we run one-two in Valencia, then the championship's still possible. But let's be real, you don't give a guy like Rossi an eight-point lead - he just has to follow me at Valencia."

Hayden falling at a crowded first corner, or suffering a mechanical failure, would have been plain bad luck and all a part of racing - but losing a world championship lead because of a team-mate's suicidal attack was plain stupidity and may cause Honda to review the wording of its 'no teams orders' rule. Certainly, it appears that Pedrosa will now have to help Hayden at Valencia.

"This extraordinary season is not over yet. Obviously our target for the next race at Valencia is for Nicky to win and for Dani to finish second which would give Nicky the riders' championship title," confirmed team manager Makoto Tanaka.

Hayden and Pedrosa have already signed to spend the 2007 season as team-mates.