With AT&T Williams drivers Nico Rosberg and Kazuki Nakajima finishing Friday practice for the Belgian Grand Prix in sixth and fifteenth positions Saturday's practice session would take on a major role in seeing if the team could improve both drivers performances, in particular Kazuki.

After the mixed weather conditions on Friday the third practice would be declared wet even though it was not raining. But parts of the circuit were damp. This is a feature of the Spa circuit. Most of the field would start the session on intermediates with half the field coming out on their installation lap. Button would pull his car off at Le Source with a problem. As usual the Ferrari's remained in their pits. As the cars circulated the track a dry line would start to appear.

With fifteen minutes of the session run the rain would start to fall again with Bourdais fastest from Heidfeld. But their times were a huge margin off the Friday times. Glock would move to the top of the times with thirty five minutes left in the session. Alonso was now second. But Piquet would move ahead of Glock. Webber would go fastest but Glock would grab the spot back on his next lap. Coulthard would go fastest but Vettel would move ahead of him but almost two seconds.

With twenty five minutes left the Williams team would finally send one of their drivers, Kazuki, while Nico remained in the pits. Kazuki was on a dry tyre. Glock would move into second also using the dry tyre. On his next lap he would go fastest by some 2.5 seconds. Using his dry tyres to advantage Kazuki would move up to second. Nico would take to the track along with several other drivers all looking to take advantage of the drying track. Kazuki was now fastest from Glock.

Nico would move into third but this would become fastest as the times fell. Glock would move ahead of Nico with fifteen minutes left in the session. Hamilton, Massa, and Kovalainen had yet to set a time. With the track drying further Bourdais would go fastest only to be beaten by Kubica. Next to take the top spot would be Piquet followed by Alonso. Piquet was passed by Hamilton running on the soft tyre.

With just the final minutes to run all the field was out on the track. As the times fell it would be Heidfeld who would set the quickest time followed by Kovalainen, Alonso, Hamilton, Massa, Vettel, Raikkonen, Nico, Piquet, and Webber. As for Kazuki he would finish the session way down the order in sixteenth. The session was very much a repeat of the final Friday session with the variable weather seeing the lap times vary greatly. It was also a repat of Friday for the Williams team with Nico in the top ten and Kazuki again struggling.

Pos  Driver        Team                      Time     Laps
 1.  Heidfeld      BMW Sauber           (B)  1:47.876 19
 2.  Kovalainen    McLaren-Mercedes     (B)  1:48.165 10
 3.  Alonso        Renault              (B)  1:48.307 19
 4.  Hamilton      McLaren-Mercedes     (B)  1:48.356 10
 5.  Massa         Ferrari              (B)  1:48.692 6
 6.  Vettel        Toro Rosso-Ferrari   (B)  1:48.768 16
 7.  Raikkonen     Ferrari              (B)  1:48.815 10
 8.  Rosberg       AT&T Williams-Toyota (B)  1:48.836 13
 9.  Piquet        Renault              (B)  1:48.946 17
10.  Webber        Red Bull-Renault     (B)  1:49.054 14
11.  Trulli        Toyota               (B)  1:49.057 16
12.  Coulthard     Red Bull-Renault     (B)  1:49.125 11
13.  Kubica        BMW Sauber           (B)  1:49.250 12
14.  Bourdais      Toro Rosso-Ferrari   (B)  1:49.256 19
15.  Glock         Toyota               (B)  1:49.535 18
16.  Nakajima      AT&T Williams-Toyota (B)  1:49.830 12
17.  Fisichella    Force India-Ferrari  (B)  1:49.949 16
18.  Sutil         Force India-Ferrari  (B)  1:50.034 16
19.  Barrichello   Honda                (B)  1:50.061 17
20.  Button        Honda                (B)  No time