SEPANG, Malaysia  -- Lewis Hamilton set the fastest time in Friday's opening practice for the Formula One Malaysian Grand Prix, reinforcing Mercedes as favorite to win Sunday's race.

Hamilton was 0.15 of a second faster than Ferrari's Kimi Raikkonen, who put in an improved showing after the team's mediocre performance in the season opener in Australia.

Hamilton's teammate Nico Rosberg - who won in Australia - was third fastest, ahead of the McLaren pair Jenson Button and Kevin Magnussen.

Reigning world champion Sebastian Vettel did less than half the laps of his rivals, indicating continued issues for the Red Bull after he retired early in Melbourne with engine problems.

The Lotus cars of Romain Grosjean and Pastor Maldonado both failed to complete a lap due to yet more powertrain failures, continuing the team's frustrating start to the era of V6 turbo hybrid engines.

Force India's Sergio Perez only did a couple of installation laps, indicating his car also had major technical issues, while Kamui Kobayashi ran only briefly before being hauled back to the garage where the floor of the Caterham was removed to repair a malfunctioning energy-store battery - the same problem that afflicted him in Melbourne.

There were no such reliability concerns for Hamilton despite the fact he used the same engine that forced his early retirement from the Australian race, with the team having repaired the misfire.

On a typically steamy, but dry, Malaysian day, many drivers struggled with the low downforce levels on the 2014 cars, with Hamilton, Fernando Alonso - who was only 11th fastest - and Williams' Felipe Massa (9th) among the experienced drivers to run off the track.

Afternoon showers were forecast for Kuala Lumpur, which may affect the second practice session.

The other top 10 drivers for the session were Toro Rosso's Jean-Eric Vergne in sixth, Vettel in seventh, Force India's Nico Hulkenberg in eighth and Williams' Valtteri Bottas in 10th.