Nicky Hayden will have a rethink with his Ducati team prior to final practice and qualifying at Phillip Island on Saturday after struggling with chatter on his Desmosedici.
Hayden finished the opening day in Australia in ninth place as the American was restricted by vibration issues on the factory machine.
“It hasn't been a great day. The conditions weren't easy for anyone,” Hayden said.
“It was cold and windy with a few spots of rain, which makes it tough on a fast track.
“I didn't have a lot of confidence in the fast corners, as the bike was moving a lot and the track felt very bumpy.
“I had a lot of chatter and vibration, so it's tough to push hard,” he added.
“Tonight we need to think about how we can improve the feeling and feedback and hopefully do a big step tomorrow.”
Hayden's time of 1m 32.654s was 0.624s behind team-mate Valentino Rossi.