After Valentino Rossi's leg-breaking accident at Mugello, Sunday's US Grand Prix at Laguna Seca might well have produced the second defining moment in the 2010 MotoGP title chase.

Jorge Lorenzo arrived in America with a reduced 47 point lead over Dani Pedrosa, who looked in with an excellent chance of claiming his third victory of the season as he led the first eleven laps of the race.

But Lorenzo became ever more threatening and was almost within striking distance of Pedrosa by lap 12 of 32, when the Honda rider suddenly lost the front of his RCV and crashed out of the lead.

It was a pivotal moment, being the first time either rider had crashed out of a race this season.

"It was clever to push Dani to the limit but not easy as well because Jorge is the championship leader and he had the most to lose, he really had to ride at the maximum to do this," said Fiat Yamaha team manager Wilco Zeelenberg.

Pedrosa's mistake handed Lorenzo a sixth victory from nine starts and a huge 72 point title lead heading into the mid-season summer break.

"We're happy Dani isn't hurt and now we have an amazing 72-point lead as we break for the half-way point of the championship," Zeelenberg added.

After Pedrosa's accident, Ducati's Casey Stoner finished second with Lorenzo's recovering team-mate, Valentino Rossi, in third.

Lorenzo celebrated his latest victory by dressing up in a NASA-type spacesuit (pictured) and performing a mock moon-walk through the corkscrew gravel, where he planted his Lorenzo Land flag.

"I am so happy to win here at Laguna Seca, it's something I've always dreamed of," said Lorenzo, who had been injured in his two previous US GP appearances.

"I rode so well today, right on the limit and I had to push very hard to stay in touch with Dani.

"He is always so strong on race day but I knew if I kept the pressure on him then there was a chance he would make a mistake and I would be able to catch him.

"I'm sorry he crashed but from then on it was very easy for me because I had a big gap from Casey.

"I have a big lead in the championship but there is half of the season left and it wouldn't be the first time a rider has lost the title with such a big lead, so we can't take anything for granted.

"I am really looking forward to some time to relax now after two very busy months. Thanks to everyone in my team for doing a brilliant job."

Round ten of the 2010 championship takes place at Brno on August 15.