Lewis Hamilton has topped the timesheets after the first practice session in Melbourne, posting a 1:23.599.

The reigning world champion's time was marginally faster than Sebastian Vettel, who was also just ahead of his new teammate for 2019, Charles Leclerc.

Max Verstappen was fourth for Red Bull, who will be looking to start its relationship with Honda off strongly this weekend.

Valtteri Bottas was fifth in the second Mercedes, but suffered a small scare late on in the session. Heading into the penultimate corner, Bottas touched the grass, which disrupted his run into the corner.

As he ran wide and flick-spun the W10, the car came dangerously close to hitting the barrier, with the rear wheels kicking up more grass.

There was one red flag during the session, which was caused by Toro Rosso rookie Alexander Albon.

The Thai-British driver lost control of his car at Turn 1 and hit the barriers, losing his front wing. Despite the red flag, Albon was able to drive the car back to the pit lane unassisted. 

Kimi Raikkonen was sixth for Alfa Romeo, ahead of Daniil Kvyat, whose session ended with complaints of his rear left tyre, as it appeared the carcass started to come through.

Pierre Gasly was eighth, while Kevin Magnussen and Nico Hulkenberg rounded out the top ten. 

Hulkenberg had a slow start to the day and was sidelined for much of the session while his mechanics worked on his car. 

His teammate and local favourite Daniel Ricciardo was only 17th, quicker than Lando Norris and the two Williams'.

The Grove outfit looked to be well off the pace, with Robert Kubica, the lead Williams driver in the session, 4.3 seconds down on pace-setter Lewis Hamilton.