ISTANBUL, May 9, 2008 (AFP) - Defending drivers world champion Kimi Raikkonen shrugged off a gearbox problem here Friday to clock the fastest time in second practice for Sunday´s Turkish Grand Prix.

The championship leading Ferrari driver swept to the top of the time-sheets with a typically stylish performance in the rain-hit afternoon at the Istanbul Park circuit.

The Finnish racer finished bottom in the opening session after being restricted to just three laps of the 5.338 kms track by the technical fault as Ferrari team-mate Brazilian Felipe Massa set the pace.

But reigning champion Raikkonen, who leads the standings by nine points after four of the 18 rounds, deposed the Brazilian in the afternoon session after a short shower had hit the track.

The drivers, reduced to 20 after the demise of Super Aguri, were finding the cooler conditions tricky after the race was moved from its traditional August date.

Raikkonen, winner in Istanbul in 2005 for McLaren, clocked a best time of one minute 27.543 seconds.

McLaren´s Lewis Hamilton, last year´s championship runner-up and second again this season, produced a late flying lap to get within 0.036secs of Raikkonen.

But the British driver, 23, looks to have a battle on his hands in the 58-lap race to prevent another Ferrari one-two.

Massa, who has won the event for the past two years in his Ferrari, was third fastest just over 0.1secs adrift of Raikkonen.

The Brazilian, 27, needs to make it three years in a row if he is to reduce his 11 point deficit to his team-mate who has won two of the opening races including the last grand prix in Spain.

Red Bull´s Scottish driver David Coulthard, whose season has been marred by a succession of crashes, went fourth fastest late on.

Raikkonen´s fellow Finn Heikki Kovalainen was fifth quickest as he showed no lasting problems from his horror smash in Spain two weeks ago when he rammed into a tyre barrier at around 165mph.

Poland´s BMW Sauber driver Robert Kubica was the only other racer to get within one second of the pacesetter, finishing almost 0.9secs down in sixth spot.

But Coulthard´s fellow Red Bull driver Mark Webber crashed out early in the afternoon session after losing control of his car at turn six.

Australian racer Webber, 31, drifted too wide and was sent spinning across the circuit before ramming into a barrier. The two front wheels of his car were ripped off although the crash was nowhere near as serious as Kovalainen´s.

Webber ended up 19th fastest after managing just four laps with only Force India´s German driver Adrian Sutil below him.