By Andrew Benson
Ferrari confirmed their status as pre-race favourites for the Belgian Grand Prix by dominating Saturday's final practice.
Raikkonen is 18 points behind championship leader Hamilton
Kimi Raikkonen was more than a quarter of a second clear of his closest rival with a lap of one minute 46.137 seconds around the Spa-Francorchamps circuit.
His team-mate Felipe Massa was second, 0.251secs behind, and just 0.119secs ahead of Fernando Alonso's McLaren.
The world champion's team-mate Lewis Hamilton was fourth fastest.
Alonso did not go out until halfway through the hour-long session as McLaren sought to solve an as-yet-unknown problem on his car.
But when he did, the Spaniard was immediately on the pace, vaulting ahead of Hamilton into third place behind the Ferraris with his first flying lap.
Hamilton then beat his team-mate's time on his second run, only for Alonso to beat him again on his own second run at the end of the session.
Hamilton, doing his third run at the same time on the same type of tyres, did not beat his team-mates time.
Alonso managed just nine laps in the session compared with Hamilton's 13 and the 16 managed by both Ferrari drivers.
That could affect his ability to tune his car fully to his liking for qualifying and the race.
Raikkonen set his best time early in the session, and was just 0.003secs slower when all the leading drivers did their runs on softer tyres at the end of the session.
At the time of his first series of laps, the Finn was more than 0.5secs clear of his team-mate.
The Brazilian improved later in the session, but the margin between the two Ferrari drivers is still significant.
And the McLarens, as expected, seem to be finding it hard to keep up with their rivals on this circuit that plays to the Ferrari's strengths.
The Italian cars have a longer wheelbase than the McLaren, which leads to an aerodynamic advantage around the long medium-and high-speed corners that largely comprise this historic track in the Ardennes mountains.
Heikki Kovalainen continued his impressive recent form to be best of the rest in fifth place in his Renault.
The Finn was 0.499secs faster than team-mate Giancarlo Fisichella, who was down in 11th place.
Jarno Trulli was sixth fastest in his Toyota, with Williams's Nico Rosberg, BMW Sauber's Nick Heidfeld, Trulli's team-mate Ralf Schumacher and the Red Bull of Mark Webber rounding out the top 10.
BMW Sauber's Robert Kubica suffered an engine failure, and will now almost certainly be hit with a 10-place grid penalty for having to have a replacement fitted.
Qualifying starts at 1300 BST.
1. Kimi Raikkonen (Finland) Ferrari 1:46.137
2. Felipe Massa (Brazil) Ferrari 1:46.388
3. Fernando Alonso (Spain) McLaren 1:46.507
4. Lewis Hamilton (Britain) McLaren 1:46.782
5. Heikki Kovalainen (Finland) Renault 1:47.065
6. Jarno Trulli (Italy) Toyota 1:47.218
7. Nico Rosberg (Germany) Williams - Toyota 1:47.251
8. Nick Heidfeld (Germany) BMW Sauber 1:47.359
9. Ralf Schumacher (Germany) Toyota 1:47.454
10. Mark Webber (Australia) RedBull - Renault 1:47.527