Nicky Hayden says a defective electronics system was the cause of his struggles in MotoGP's third round of the season at Estoril.
In contrast to Ducati stablemate Valentino Rossi, who took his year's best finish of seventh, Hayden was rarely in contention for the top 10 and ended up a distant 11th, more than one minute behind race winner Casey Stoner.
Having beaten Rossi in the previous two races, Hayden explained that an electrical glitch had sometimes left him without effective engine braking or power, resulting in a ruined and uncomfortable race.
"It was really impossible to ride - just impossible," Hayden said. "On the straight sometimes I had no power: I was opening the throttle and nothing happened.
"Perhaps the biggest problem was the engine braking, this weekend I was using a lot for the downhill stuff and I just didn't have it. I didn't know what was wrong at the start, but in sixth gear it felt like I wasn't running and when I noticed the lap-time I knew immediately.
"It wasn't easy, [it was] quite dangerous as all of a sudden I would lose power sometimes. Not an enjoyable race at all."
Hayden said his race was made all the more disappointing by the fact he and Ducati had run so well in the morning warm-up.
"It was a shame because, while I wasn't going to fight for the podium, this morning was the first time all weekend I felt near qualifying pace. I did that twice and was very steady, and the team really did a good job because all weekend we had been making changes and not finding a lot and then this morning the bike was better from the first lap. It was a tough race, but I just tried to ride around and get some points."