Lewis Hamilton laid down a marker as he led a Mercedes one-two in the new Formula One season's first free practice at the Australian Grand Prix on Friday.
The triple world champion outstripped his new team-mate Valtteri Bottas by the large margin of 0.583 seconds with his fastest lap of 1:24.220 at Albert Park.
Finland's Bottas slotted smoothly into the Mercedes team environment with a best lap of 1:24.803 as the new generation of F1 cars took to the track.
Mercedes were the only team to run Pirelli's quickest tyre, and Hamilton's time was more than three seconds faster than his best lap in last year's corresponding free practice in Melbourne.
The Red Bull pair, Australia's Daniel Ricciardo and Dutch youngster Max Verstappen, were third and fourth fastest.
Ricciardo, bidding to become the race's first Aussie winner in 37 years, posted 1:24.886, while Verstappen registered 1:25.246.
Ferrari gave little away in opening practice with Sebastian Vettel sitting out much of the session as the Scuderia declined to use up engine life on the dusty street circuit.
Vettel put in a competitive lap time in the final 15 minutes with a 1:25.464 on supersofts.
McLaren struggled with Fernando Alonso clocking the 14th fastest time, while the car of team-mate Stoffel Vandoorne suffered a water leak and the young Belgian finished last of the 20 runners.
PIRELLI & C. SPA