Maverick Vinales led Jack Miller in a delayed opening MotoGP FP1 ahead of the Australian Grand Prix, while newly-crowned five-time world champion Marc Marquez crashed.
An oil spill in the early stages of Moto3 FP1 meant the opening MotoGP session of the weekend was delayed by almost two hours, with Vinales securing top spot early with a 1:29.952s.
Home hero Miller set the early pace aboard his Pramac GP17 Ducati with a 1:36.260s, with 2016 race winner Cal Crutchlow taking over with a 1:31.588s.
Honda stablemate Marquez went two tenths quicker with a 1:31.376s, which was matched by Yamaha's Vinales moments later.
Marquez reclaimed top spot from his compatriot with a 1:30.500s, while the sister Yamaha of Valentino Rossi moved into second, albeit half a second back from the Honda rider.
Crutchlow bested Marquez by 0.060s, before Vinales went on a run of session-best laps, which culminated in the first sub 1:30s time of the day with a 1:29.952s.
Vinales' effort came under threat late on by Miller, who moved up to second with a 1:29.989s, but remained top of the pile, while the sister Pramac bike of Danilo Petrucci completed the top three.
Andrea Dovizioso made it three Ducatis in the top four as he put his works GP18 up to fourth with a 1:30.121s, with Crutchlow shuffled back to fifth at the chequered flag.
Marquez suffered a late fall at the MG hairpin, and was unable to improve on sixth as a result, but walked away from the heavy fall unscathed. 13-placed teammate Dani Pedrosa fell midway through the session at Doohan corner.
Andrea Iannone was top Suzuki runner in eighth ahead of Tech3's Johann Zarco, while Karel Abraham jumped up to ninth with a late effort of 1:30.772s in his first session on the Nieto GP17.
Rossi completed the top 10 from KTM's Pol Espargaro, while Alvaro Bautista ended his first session on Jorge Lorenzo's factory Ducati 14th and a second from teammate Dovizioso.
Bautista's stand-in at Nieto Mike Jones completed the 24-rider field, the Australian just over five seconds off the pace in his first MotoGP outing since Phillip Island 2016.
