World champion Fabio Quartararo said he had room for improvement after finishing fourth behind dominant Frenchman Johann Zarco at a windy second practice session for the Australian Grand Prix on Friday.
With recent torrential rain clearing to a cool, dry day at Phillip Island, Zarco blitzed the picturesque waterfront circuit with a best lap of one minute and 29.475 seconds.
The Ducati-Pramac rider, who is still targeting a first win in his sixth season as a premier-class competitor, was also fastest in the first session.
Italian Marco Bezzecchi, in his rookie MotoGP season, was second-quickest, 0.038 seconds behind on a Ducati, with Spanish Honda rider Pol Espargaro third ahead of championship leader Quartararo.
Frenchman Quartararo, who has posted a string of poor results to leave the title race wide open, was 0.139 seconds off the pace, but said he could get better.
"A pretty good day, this morning was tricky, this afternoon was better. I'm happy to be in the top five and I think we have a few things to try tomorrow to improve," he said.
"I felt like I was running well and feeling well also and that I have a margin in a few corners that can make me win, one-tenth here and another there."
Quartararo is desperate for points this weekend after claiming only eight from the last three races on his Yamaha.
His lacklustre form has left him with only a slender two-point lead in the standings from Italian Francesco Bagnaia on a Ducati – who came eighth in second practice – with three grands prix left.
After 17 races, five riders are within 40 points at the top of the title race with Spain's Aleix Espargaro (Aprilia), Italian Enea Bastianini (Ducati) and Australian hope Jack Miller (Ducati) all still in contention.
Espargaro was seventh-fastest and Bastianini ninth.
But the newly married Miller, the form rider who earned more points than anyone else in the recent triple-header of races, left his final run too late and only finished 13th.
"Felt good this morning, the bike was working relatively well, but this afternoon I had a little issue with the rear and I wasn't able to really push or put a lap together," said the home town hero.
"We've got some ideas of what we need to change for tomorrow. Around Phillip Island, 0.5secs off and I'm 13th. But that's the way it goes."
Six-time world champion Marc Marquez, a three-time winner at Phillip Island, was fastest for much of the session until the main contenders switched to soft rear tires for the final five minutes and he ended sixth.