The reigning world champion headed Bottas by 0.551s, as Red Bull edged Ferrari to be best of the rest.

Ferrari's Sebastian Vettel was the first car to hit the track as he led the initial burst of installation runs, but it took 20 minutes for anyone to set a time.

The first flying lap came from Williams rookie Sergey Sirotkin, but his 1m32.057s did not stand as the benchmark for long. Within five minutes the big teams began to make their mark, with Kimi Raikkonen and Valtteri Bottas briefly going quickest before the Red Bulls hit the front.

Max Verstappen twice grabbed P1 from teammate Daniel Ricciardo – interrupted by Hamilton's first spell atop the times – and Verstappen was the first driver to dip below the 1m25s mark on a 1m24.959s.

Hamilton stamped his authority on the session not long after the half-hour mark, first lapping 0.022s quicker than Verstappen and then improving to 1m24.531s.

After a mid-session break for all 10 teams, Bottas emerged on a new set of ultrasofts and lapped 0.046s slower than Hamilton, but the four-time champion re-established a commanding lead with a 1m24.026s to go over half a second clear.

Bottas could not get any closer to Hamilton over the rest of the session, and although Verstappen improved his time after switching to supersofts, third and 0.745s off the pace was the best Red Bull could manage.

Ferrari split the two Red Bulls and occupied fourth and fifth place, with Raikkonen using soft tyres to lap a tenth quicker than Vettel, who made a mistake on his first flying lap on supersofts but improved on his second.

Ricciardo ended the session sixth fastest, a quarter of a second behind Verstappen but comfortably clear of an ultra-tight midfield headed by Romain Grosjean.

Haas looked strong in pre-season testing and Grosjean continued that form in Australia by lapping 1.7s slower than Hamilton on a 1m25.730s – as a second covered the Frenchman in seventh to Sergio Perez's Force India in 16th.

Fernando Alonso ended up slightly slower than Grosjean after McLaren recovered from a difficult start to FP1 to end up with both cars in the top 10.

Alonso and Stoffel Vandoorne spent most of the first hour in the garage – Alonso suffered an exhaust problem while Vandoorne was largely absent save for a run that featured a "driveability" issue.

When Alonso emerged for proper running in the final half an hour he made quick progress up the order and eventually settled into eighth on a 1m25.896s, on supersofts, but would have been faster without a scruffy final sector.

Vandoorne used soft tyres to rise to 10th, half a second behind Alonso, as Carlos Sainz's supersoft-shod Renault split the MCL33s.

Rookie Sirotkin outpaced Williams teammate Lance Stroll by a tenth, with Pierre Gasly recording the 11th fastest time on his Albert Park debut for Toro Rosso-Honda.

Nico Hulkenberg was 13th quickest, 0.6s adrift of Renault teammate Sainz, but ahead of the Force Indias of Esteban Ocon and Perez – who were split by Stroll.

Kevin Magnussen (Haas), Brendon Hartley (Toro Rosso) and the Saubers of Marcus Ericsson and Charles Leclerc completed the timesheet.

Pos	Driver	Chassis	Engine	Laps	Time	Gap
1	Lewis Hamilton	Mercedes	Mercedes	27	1'24.026
2	Valtteri Bottas	Mercedes	Mercedes	29	1'24.577	0.551
3	Max Verstappen	Red Bull	TAG	26	1'24.771	0.745
4	Kimi Raikkonen	Ferrari	Ferrari	23	1'24.875	0.849
5	Sebastian Vettel	Ferrari	Ferrari	22	1'24.995	0.969
6	Daniel Ricciardo	Red Bull	TAG	25	1'25.063	1.037
7	Romain Grosjean	Haas	Ferrari	24	1'25.730	1.704
8	Fernando Alonso	McLaren	Renault	16	1'25.896	1.870
9	Carlos Sainz Jr.	Renault	Renault	23	1'25.922	1.896
10	Stoffel Vandoorne	McLaren	Renault	15	1'26.482	2.456
11	Pierre Gasly	Toro Rosso	Honda	25	1'26.494	2.468
12	Sergey Sirotkin	Williams	Mercedes	25	1'26.536	2.510
13	Nico Hulkenberg	Renault	Renault	25	1'26.583	2.557
14	Esteban Ocon	Force India	Mercedes	30	1'26.605	2.579
15	Lance Stroll	Williams	Mercedes	30	1'26.636	2.610
16	Sergio Perez	Force India	Mercedes	26	1'26.767	2.741
17	Kevin Magnussen	Haas	Ferrari	13	1'27.035	3.009
18	Brendon Hartley	Toro Rosso	Honda	16	1'27.745	3.719
19	Marcus Ericsson	Sauber	Ferrari	28	1'27.964	3.938
20	Charles Leclerc	Sauber	Ferrari	28	1'28.853	4.827