Yamaha MotoGP rider Valentino Rossi expects Motegi's track layout to cause him "more problems" than the previous round at Aragon, as he continues his recovery from injury.
Rossi broke his right leg in late August but made a sooner-than-anticipated return to MotoGP track action at Aragon, where he finished fifth.
Three weeks on from that round, Rossi says his condition is "a lot better" than it was at the Spanish track - but admits this weekend's Japanese Grand Prix could be more of a challenge because of the Motegi circuit's layout.
He said: "There are more right corners. Aragon was good for me, because it has a lot of lefts, like Phillip Island - maybe here [I will have] some more problems.
"[More] hard braking also is difficult, because with less power in the leg I have to force more with the shoulder.
"After Aragon for two or three days I had some pain, because I unfortunately I have less help from the leg. But we will have to see.
"I hope I can be OK, because my physical condition is a lot better compared to Aragon."
Rossi added that not being able to train as normal for Motegi has contributed to him still not being at full fitness.
He said: "There is still some pain, but for me on the bike I suppose I can ride, because anyway the leg is better than in Aragon.
"I'm not 100%, for sure. Also I have to modify the training, but I feel not so bad.
"Unfortunately I cannot make my normal [preparation] work, I can't run, so I have to do something different."
Having missed a race due to his injury, Rossi is now 56 points adrift of Honda's championship leader Marc Marquez, with four rounds left to run and 100 points still up for grabs.
Yamaha's main hopes for the title lie with teammate Maverick Vinales, who trails Marquez by 28 points.
Asked whether Yamaha has asked him to help Vinales' championship challenge, Rossi said: "At this moment, no. Usually Yamaha don't do [team orders].
"But it depends very much on the championship. If it's very close, maybe it's possible.
"It's an interesting situation because all three factories [Yamaha, Honda, Ducati] have a second rider who is fast and maybe can help the first rider for the championship."