Edwards cites engine braking problem

Despite taking pole position, he quickly fell down the order in the race and finished three laps down in 12th after pitting for wet tyres several laps too early.

"It's strange - we had a crash yesterday for a reason that we know, almost like too much engine braking or something like that," Edwards told BBC television.

"It seemed that I'd go in and brake, and as soon as I tried to tip it in it would come around sideways.

"Valentino (Rossi) holds the clutch deep into the corner, I pretty much let it go when I've finished braking. We've just got a couple of issues that we need to figure out. With the 800cc (bike) it's more exaggerated, more so than last year. We'll just have to work on it."

Edwards added that Yamaha also need to work specifically on their wet weather performance.

"We haven't had that much wet testing, only one day I guess, with the 800s, and this is a different track and different tyres, so we've got to get back to the drawing board and see what we need to do," he said.

The American has only managed one podium finish so far in 2007, despite qualifying on the front two rows for every race.

He compared his current run of form to that of 125cc rider Mattia Pasini, who has retired from four of this year's five races after taking pole position for four of them.

"I'm not even friends with Pasini, and his luck seems to be rubbing off on me..." Edwards joked. "A crash, an 11th and then a 12th - it's just a horrendous last few races."