Ferrari duo Felipe Massa and Kimi Raikkonen topped the timesheets in practice on Friday ahead of Sunday's Belgian Grand Prix.

Massa set the fastest time in the first run round the flowing Spa circuit, clocking one minute, 47.284 seconds with Raikkonen 0.339 seconds behind.

Lewis Hamilton was third for McLaren ahead of team-mate Heikki Kovalainen.

With the Englishman leading the title race by six points from Massa, Ferrari are desperate for a Belgian win.

After a spell of testing in Monza, Ferrari believe they have ironed out their technical problems and are ready to launch a renewed attack on the drivers' title.

Massa is looking to build on his victory in Valencia two weeks ago and was in a class of his own in first practice.

The Brazilian knocked out fastest lap after fastest lap in the closing stages in Spa as Raikkonen and Hamilton were unable to close him down.

Hamilton was 0.594 seconds adrift of Massa with Kovalainen and fifth-placed Renault's Fernando Alonso the only other drivers to finish within a second of Massa.

His Ferrari team-mate Raikkonen is also hoping to use his experience at Spa, where he has won the last three Grands Prix, to propel himself back into the title race.

The defending champion is 13 points behind Hamilton but has set his sights on good results at Spa and Monza, both tracks which suit the Ferraris.

Raikkonen's car broke down because of engine trouble in Valencia but the Finn is confident those problems have now been resolved.

Mark Webber's Red Bull finished sixth fastest followed by the Toro Rossos of Sebastien Bourdais and Sebastian Vettel.

Toyota's Timo Glock and the second Renault of Nelson Piquet rounded out the top 10, with the latter a huge 1.784 seconds behind Massa.

David Coulthard was 15th for Red Bull, with the rear of the field brought up by Honda duo Jenson Button and Rubens Barrichello, both a dismal three seconds down.

First free practice session times for the Belgian Grand Prix:

1. Felipe Massa (Brz) Ferrari 1 min 47.284 secs

2. Kimi Raikkonen (Fin) Ferrari 1:47.623

3. Lewis Hamilton (GB) McLaren-Mercedes 1:47.878

4. Heikki Kovalainen (Fin) McLaren-Mercedes 1:47.932

5. Fernando Alonso (Spn) Renault 1:48.104

6. Mark Webber (Aus) Red Bull-Renault 1:48.428

7. Sebastien Bourdais (Fra) Toro Rosso-Ferrari 1:48.557

8. Sebastian Vettel (Ger) Toro Rosso-Ferrari 1:48.958

9. Timo Glock (Ger) Toyota 1:48.997

10. Nelson Piquet (Brz) Renault 1:49.068

11. Robert Kubica (Pol) BMW Sauber 1:49.139

12. Nick Heidfeld (Ger) BMW Sauber 1:49.185

13. Nico Rosberg (Ger) Williams-Toyota 1:49.611

14. Jarno Trulli (Ita) Toyota 1:49.625

15. David Coulthard (GB) Red Bull-Renault 1:49.849

16. Giancarlo Fisichella (Ita) Force India-Ferrari 1:49.986

17. Adrian Sutil (Ger) Force India-Ferrari 1:50.117

18. Kazuki Nakajima (Jpn) Williams-Toyota 1:50.125

19. Jenson Button (GB) Honda 1:50.464

20. Rubens Barrichello (Brz) Honda 1:50.905