Casey Stoner admitted that he was at a loss to explain the crash that took him out of the lead of the Czech Grand Prix.
The reigning champion was holding off Valentino Rossi at the head of the field when he fell on lap six, and with his title rival Rossi going on to take a dominant victory, Stoner is now 50 points adrift in the standings.
"Things were going according to plan until the crash," Stoner said. "I was doing the same lap time over and over and I was quite happy with the pace I was running.
"The crash came out of the blue, that corner was an easy one but I lost the front and it happened very quickly, very suddenly and I didn't manage to save it. It's a hard one to explain and we will look at the data but sometimes this kind of crash happens at this level of racing and it was my mistake."
He conceded that the accident was a major blow to his title aspirations.
"We knew that we needed to win this race - and more - in order to close down Valentino's advantage so this makes the championship very difficult for us," Stoner said.
"Anything can happen in racing but fifty points is a big gap against such a strong and consistent competitor. Anyway I never throw in the towel, nor does anybody at Ducati, and we will keep fighting until the end."
Team boss Livio Suppo agreed that Stoner's error could have cost Ducati this year's title, but pointed out that the Australian has been virtually error-free since joining the squad.
"I'm obviously disappointed for Casey because after another incredible weekend it's a small mistake - his first in a race since he's been riding for us - has cost us very dearly," said Suppo.
"Anyway, we have to think positive and continue to work hard to put him in the right conditions to ride as hard as that in the six races that are left."