Lewis Hamilton has topped the opening Formula One practice session at the Australian Grand Prix.
The Mercedes driver sat atop the leaderboard for much of the 90 minute session, as drivers came to grips with the Albert Park Circuit, the Brit setting a 1:24.026 in the last 30 minutes on the Ultrasoft compound.
Team mate Valtteri Bottas finished second quickest, just 0.5s off Hamilton’s pace, ahead of the Red Bull of Max Verstappen.
Kimi Raikkonen was the lead Ferrari in fourth, while Sebastian Vettel, who was the first man out on track at the drop of the green flag, took out fifth fastest after improving in the final third of the session.
Aussie Daniel Ricciardo grabbed sixth, 0.3s adrift of team mate Verstappen, with Romain Grosjean the next best aboard his Haas in seventh.
Struggling with an exhaust issue in the first hour of the hit out, Fernando Alonso only completed a handful of laps, but managed eighth in his McLaren after entering the circuit for the first time in the last 20 minutes.
Carlos Sainz in the Renault finished ninth quickest, while the sister McLaren of Stoffel Vandoorne completed the top ten.
F1 debutant Sergey Sirotkin was the first man to set a timed lap (1:28.125s) in the session, and the first to set an official timed lap in the 2018 season aboard his Williams.
The Russian driver was followed up by Ricciardo, before the circuit became busier at the end of the first 30 minutes after a quite start.
Verstappen was the first to dip into the 1min 24s, with a 1:24.959s behind the wheel of his Red Bull on a set of Ultrasofts, until Hamilton bettered the Dutchman’s lap to go quicker by 0.022s.
After a lull in track activity, Bottas returned to the circuit in his Mercedes as the clock counted down to the last half hour, moving to second fastest on a set of Ultrasofts.
He was joined on circuit minutes later by most of the field as the timing screens began to light up, with Hamilton bettering his time to a 1:24.147s.
Alonso came onto the circuit with 20 minutes to go, his first lap, a 1:26.638s put the Spaniard 14th fastest, before eventually moving up to eighth.
Vettel improved on a set of Supersofts to go fifth with a 1:24.995s, just as a flurry of track activity kicked off in the last ten minutes.
At the chequered flag, Toro Rosso’s Pierre Gasly finished 11th, while Kiwi team mate Brendon Hartley in 18th, only completed 16 laps.
Williams’ Sirotkin claimed 12th, with the top Force India 14th in the form of Esteban Ocon.
Practice 2 gets underway at 1600 AEDT.