It's too early to say how much we have improved since Melbourne Kimi Raikkonen Full practice results

The Finn, whose team had an appalling first race of the season, set the pace in Friday practice at the Sepang track.

Raikkonen set a time of one minute 34.395 seconds to head Ferrari's Michael Schumacher, with Williams driver Ralf Schumacher with third overall.

Mark Webber of Jaguar and Williams' Juan Pablo Montoya were next up.

Michael Schumacher was quickest in the first session on Friday with a lap of 1:34.437.

At the time, that was 0.9secs quicker than team-mate Rubens Barrichello and 1.8secs quicker than the fastest man not in a Ferrari

Schumacher was more than half a second slower in the second hour, but his earlier time was still quicker than anyone bar his brother and Raikkonen.

Lap Sepang with Jarno Trulli

Barrichello was only 10th fastest in the afternoon.

It remains to be seen whether the result was due to Ferrari's tyre supplier Bridgestone again struggling compared in the high temperatures of Malaysia, as they have done for the last two years.

Michelin supplies all Ferrari's main rivals.

Raikkonen was almost 0.298secs up on Ralf Schumacher and 0.659secs faster than Webber as all four drivers bettered the current race and qualifying laps records at Sepang, where track temperatures reached 53C.

Ferrari's rivals hope the team will struggle in the heat

But the Finn played down the significance of his performance.

Raikkonen said: "A productive practice session, and of course it's pleasing to be fastest, but it's still early days.

"We went through our tyre evaluation programme, and the car feels good and is handling well, but we will see what happens in qualifying.

"It's definitely too early to say how much we have improved since Melbourne, but I'm looking forward to the rest of the weekend."

Ralf Schumacher added: "I have to say that I am very happy with the car. We focused on our homework intensely and have completed our programme without too many problems.

"This fact makes me very confident for tomorrow's qualifying."

Renault's Jarno Trulli, Sauber's Felipe Massa, Renault's Fernando Alonso and McLaren's David Coulthard all shone in the afternoon session to post faster times than Barrichello.