Marc Marquez made a late move to the top at the end of opening practice for MotoGP's final Australian Grand Prix at Phillip Island.
Ducati's title hope pipped previous pacesetter Raul Fernandez by 0.048 seconds, with Marquez running much older tyres than the Trackhouse Aprilia for his lap.
Fernandez was one of three riders to have violent crashes during the session, carefully protecting the hand he injured at Mandalika a fortnight ago as he tumbled through the gravel all the way to the tyre wall. He was unhurt and able to resume - and go fastest for a while - on his second bike.
Home hero Jack Miller had a few glorious minutes on top of the timing screens on fresh tyres, but immediately crashed at the first corner just after putting his Pramac Yamaha in an unlikely first place. Miller's time still held up for third, though, ahead of Marco Bezzecchi's Aprilia.
Championship leader Jorge Martin was seventh on the second Aprilia.
Iker Lecuona - back from World Superbike duty again to stand in for the injured Fermin Aldeguer at Gresini Ducati - had the most worrying crash, as his bike bounced back off the tyre wall and flew over him before he'd come to rest. He was also unhurt.
The eventful morning also featured a dramatic smokey failure for Brad Binder's KTM. Binder rejoined on his spare bike and finished the morning in 11th.