Lewis Hamilton started the new Formula 1 season using fastest time from the first exercise session at the Grand Prix.
The world winner had emphasised on Thursday that he believed Mercedes were behind Ferrari heading into this season.
Just 0.193secs covered the major four, with Red Bull’s Max Verstappen up.
British-born Thai Alexander Albon, a rookie forcing for Toro Rosso, brought the session to a brief halt having a wreck at spin Two.
The episode knocked off front but Albon surely could drive the vehicle back into the pits.
The other new drivers, Britain’s Lando Norris and George Russell, started attentively on the Albert Park street track, which can be notorious for its own dirt and lumps and at which it’s easy to lose the vehicle and damage it.
Norris stopped the session 18th, four regions and 0.6secs away team mate Carlos Sainz. Russell was last and 0.8secs off his Williams teammate Robert Kubica.
Williams were, as expected, adrift of this trunk of this field – Kubica was two minutes away from the next slowest car, which was Norris.
Part of this margin was tyres – Williams only ran the moderate tyre while many the others put their days on the quickest soft – however that still leaves the Williams a lot higher than a second off the back of grid.
At front, Hamilton’s performance undermined Mercedes’ asserts that these were behind Ferrari.
The world champions led how throughout the session, Bottas starting with the quickest period when running the moderate tyre, before Hamilton shining ahead by 0.267secs to the soft.
Bottas ran wide at the penultimate corner and narrowly avoided clouting the walls while trying to improve his period.