Melbourne - Defending Formula One champion Lewis Hamilton topped the timesheets for Mercedes at the first free practice for the Australian Grand Prix on Friday, edging Ferrari in an eventful session.
The Briton lapped Albert Park in one minute 23.599 seconds, pipping championship rival Sebastian Vettel by 0.038 seconds on a warm and sunny afternoon at the lakeside circuit.
Vettel's rookie team-mate Charles Leclerc was third fastest, 0.074 seconds slower than Hamilton, raising hopes of a proper battle between the championship's leading teams.
Max Verstappen was fourth quickest for Red Bull, less than two-tenths of a second shy of Hamilton.
Hamilton's team-mate Valtteri Bottas was fifth quickest but the Finn, under pressure to keep his race seat, blew a chance to improve his time with a spin off the track, one of a number of incidents as teams struggled to get to grips with their cars.
Home hope Daniel Ricciardo had an underwhelming debut with Renault, clocking only the 17th fastest time.
His team-mate Nico Hulkenberg was left confined to the garage for most of the session as engineers worked on an electrical problem but the German later emerged to clock the 10th fastest lap.
With half an hour left in the session, Williams rookie George Russell came to a halt at the front of pit-lane and needed to be rolled back to the garage.
British-born Thai debutant Alexander Albon also had a tough start, spinning his Toro Rosso at turn two and having a low-impact crash to lose his front wing and cause a brief halt in the session.
Pole Robert Kubica, returning to Formula One after an absence of more than eight years, ran into the grass but was otherwise unscathed and ended up posting the 19th fastest lap for Williams.