Valentino Rossi believes Ducati is in better shape in Japan than it had been in the previous event at Aragon.
The former champion is continuing with the partially aluminium chassis introduced in Spain, and was eighth quickest today.
"We made progress with the bike throughout the day, and as a result we improved our lap times, dropping below 1m48s," said Rossi.
"The pace is still far from the top, but not bad for now. There are a number of things to resolve, but we're definitely not in the situation we were at Aragon, where we always had big problems with rear grip. That's not the case here.
"We worked on weight distribution, loading the front a little more, and it's better. Tomorrow we must try to drop into the low 1m47s range. That's our goal."
Rossi's team-mate Nicky Hayden was the faster Ducati rider today, taking third in the morning and sixth in the afternoon, although Rossi noted that the American "chose to ride mainly with the soft tyre" today.
Hayden was cautiously optimistic about his performance.
"I had fun riding the bike today, and that's important," said Hayden. "This morning was really encouraging, because I could ride comfortably, and we really haven't made many changes throughout the day. I've steadily got a little bit faster, but the others made a bigger jump in the afternoon.
"I've certainly had worse Fridays this year, but we've got a long way to go if we want to be near the front on Sunday afternoon."