MELBOURNE (AFP) - World champion Lewis Hamilton made an ominous start to the season as he led a Mercedes one-two in opening practice for the Australian Formula One Grand Prix on Friday (March 23).

Hamilton clocked a best time of 1min 24.026sec among his 27 laps to be a half-second quicker than team-mate Valtteri Bottas (1:24.577) in Melbourne.

The 33-year-old Briton is gunning for his fifth world title in 2018, an achievement which would match the legendary Juan Manuel Fangio and leave him just two adrift of Michael Schumacher's all-time record.

Dutchman Max Verstappen was third quickest in his Red Bull with 1:24.771, some 0.745sec behind Hamilton, while his Australian team-mate Daniel Ricciardo was sixth.

Ricciardo was heard saying on the team radio: "Still disconnected. I struggle with the front when leaning on it, and I feel like the rear hurts on exit still."

The Ferraris of Kimi Raikkonen and Sebastian Vettel were fourth and fifth fastest, but, significantly, between 0.8-0.9secs slower than Hamilton.

Ferrari raced on ultrasofts while Red Bull's best times came on supersofts.

Hamilton has won twice in Melbourne, in 2008 and 2015, among his 62 wins in 208 grands prix.

He already holds the record for most pole positions with 72, ahead of Schumacher's 68.

It was yet another frustrating session for Fernando Alonso in his McLaren. He only got on the track after a long hold in the pits with an exhaust problem.

But the Spaniard eventually finished eighth quickest, just behind Romain Grosjean in a Haas.

Alonso has already forecast this weekend's Australian GP will be the low point of McLaren's 2018 season as they grapple with the transition to their new Renault engines.

McLaren's off-season testing programme was hit by a series of mechanical issues.