Casey Stoner says his ankle injury is still proving a hindrance and detracting from his performances at Motegi.
The Australian returned to action on Friday after missing the past three races, the legacy of ankle fractures and ligament damage suffered in a heavy qualifying crash at Indianapolis.
While Stoner has officially been cleared to race, he admits he is having to compensate for his ankle and cannot therefore ride at his absolute maximum. He finished fourth and seventh fastest respectively in the opening two practice sessions in Japan.
"Of course I'm not feeling 100 percent as it is, so I wanted to get a reasonable feeling with it before I start pushing," the Honda rider explained. "At the moment the acceleration points are causing me most difficulty as there are many areas at this circuit where the bike wants to wheelie and you need to keep your body and weight over the front of the bike.
"Unfortunately, my foot doesn't want to bend far enough to help me move forward so I'm having to pull myself forward which is giving me issues with my arms as they are working a lot harder than usual. We'll keep working tomorrow and see what we can do."
Stoner was also left frustrated by bike issues during the two sessions. His first bike suffered a failure in the opener, while he lost time to a brake fault during second practice.
"This morning we had our first bike fail on us so we lost valuable time, then in the second session we had a brake issue and spent a lot of time in the garage fixing that also," he said. "We spent the two sessions trying to find a nice balance with the bike, [but] today was a little disappointing."