Valentino Rossi proclaimed seventh place at Motegi as the best he could do with the factory Ducati.
The Italian conceded the result reflected his potential on the Desmosedici at the Twin Ring circuit and revealed he is continuing to struggle on the exit of corners as the rear wheel spins up on acceleration.
“I think we did the best that we could over the whole weekend. We worked well on the bike, and I had a good setting for the race today,” he said.
“Unfortunately, this is our potential at the moment, and our pace still isn't at the same level as the others, especially in the early laps.
“Today I rode at the maximum for the whole race, I tried to catch [Stefan] Bradl, and I got closer near the end.
“I think we've found consistency since we've had the new frame and swingarm, but there's still work to do.
“We still lose a lot on acceleration, where we're not able to put all the horsepower to the ground because the tyre spins too much, especially exiting the slower corners,” Rossi added.
“Anyway, we'll try our best until the end and see how it goes.”
Rossi finished 10 seconds ahead of team-mate Nicky Hayden and was a second-and-a-half behind LCR Honda's Stefan Bradl in sixth.