Heidfeld is currently under pressure to retain his seat with BMW Sauber for next season, but ahead of Saturday's qualifying session at the 4.35-mile Spa circuit, Heidfeld should be buoyed by his performance in the final 60 minutes of practice.

The German topped the timesheets with a lap of one minute 47.876 seconds, with McLaren's Heikki Kovalainen 0.289secs adrift in second and Fernando Alonso third in his Renault.

World championship leader Lewis Hamilton's time of 1:48.356secs in his McLaren meant he was fourth.

Twenty seconds after that, Felipe Massa finally emerged from his garage, completing just six laps overall, with his best on a heavy fuel load good enough for fifth, finishing 0.816secs behind Heidfeld.

Toro Rosso's Sebastian Vettel was sixth, with Raikkonen seventh, followed by the Williams of Nico Rosberg, Renault's Nelson Piquet and the Red Bull of Mark Webber.

David Coulthard was 12th quickest in his Red Bull, 1.249secs down on Heidfeld, whilst it was another miserable morning for Honda.

Rubens Barrichello was down in 19th, over two seconds off the pace, whilst Jenson Button failed to set a time.

The Briton's session came to an abrupt halt at the opening La Source hairpin, and just two minutes in, due to an apparent technical fault.