Casey Stoner crashed out for the second time in three 2010 starts after his factory Ducati slid out from under him on lap 3 of Sunday's French Grand Prix at Le Mans.

The Australian had just taken fourth place from team-mate Nicky Hayden when the tumble occurred, which has had disastrous consequences for his world title hopes. Stoner is now 59 points - over two race wins - behind world championship leader Jorge Lorenzo.

Stoner was at a loss to explain why he keeps falling - he also crashed in practice at Jerez - but suggested that when he drops the pace due to slower riders ahead of him, it unloads the front.

"I'm really disappointed because the bike has felt great all weekend, I've been pushing the front wherever I wanted but for some reason when the race has come around it felt like it was going to fold," he said.

"It's something we have to get to the bottom of and we need to do it soon because it is not good to start the season with only one finish from three races.

"I haven't changed anything with my riding style but if I need to do something then we have to work out what and I can do it.

"Maybe it's because when I'm behind slower riders in the race I'm not able to put the same pressure on the front.

"I'm not sure at the moment, to be honest, so we need to sit down and work out what's best for the next race."

But team manager Vittoriano Guareschi felt that Stoner had been pushing hard when he fell, rather than backing off, and pointed out that he had clear track ahead of him.

"Today we had the possibility of having a good race, as we saw with Nicky, but it didn't turn out that way for Casey, who crashed when he was trying to make up ground on the top three," said Guareschi.

"He lost the front and now we're all working together to try and work out why. I know that Casey will bounce back in the next race, ready to give it all as always and we'll be working hard to allow him to show his huge talent."

Hayden claimed fourth for the third time this year.