On a cold, damp and miserable morning at Spa, Valtteri Bottas set the pace in final practice having edged ahead of Daniel Ricciardo.
It was a slow start to final practice as the hour-long session began on a wet track.
But with no rain falling and the track drying quickly, all but three drivers opted to wait before getting down to business.
Only Jules Bianchi, Max Chilton and Andre Lotterer, set times in the first half of FP3.
A few minutes later Esteban Gutierrez headed out with his lap times prompting the rest of the field to venture out.
Gutierrez had a brief spell at the top of the timesheets as did Pastor Maldonado, Daniil Kvyat and Bottas. The Williams driver had the P1 time down to a 1:51.583 when the two Mercedes runners hit the track.
However, neither Nico Rosberg nor Lewis Hamilton were able to overhaul the Finn on their first attempts, going second and fourth respectively.
That became third and fifth as Fernando Alonso hit the front with a 1:51.218. His reign was short-lived as the Mercedes duo came through first and second having traded fastest sector times.
Rosberg was quickest in sector one, then Hamilton, Rosberg went quickest in sector two, then Hamilton, Rosberg went quickest with a 1:50.023 and then Hamilton did a 1:50.022.
In the final ten minutes, Raikkonen headed out on the soft tyres went quickest before he was dropped by Bottas. Rosberg could only manage second while Hamilton was fourth. Both Mercs, though, had time for a second flying lap.
Those, however, didn't help and they also lost out to Daniel Ricciardo, who put in a late effort to go second.
It was Bottas, though, who finished quickest of all with a 1:49.465.
Meanwhile, Sebastian Vettel finished down in 13th place with just ten laps as a brake duct cover was sucked into the duct, again costing him track time.
01 Valtteri Bottas Williams 1:49.465 12 laps
02 Daniel Ricciardo Red Bull 1:49.733 +0.268 9 laps
03 Nico Rosberg Mercedes 1:49.739 +0.274 13 laps
04 Kimi Raikkonen Ferrari 1:49.817 +0.352 9 laps
05 Lewis Hamilton Mercedes 1:49.817 +0.352 13 laps
06 Fernando Alonso Ferrari 1:49.890 +0.425 9 laps
07 Daniil Kvyat Toro Rosso 1:49.893 +0.428 11 laps
08 Jenson Button McLaren 1:50.203 +0.738 11 laps
09 Felipe Massa Williams 1:50.423 +0.958 11 laps
10 Jean-Eric Vergne Toro Rosso 1:50.535 +1.070 10 laps
11 Sergio Perez Force India 1:50.592 +1.127 12 laps
12 Kevin Magnussen McLaren 1:50.748 +1.283 11 laps
13 Sebastian Vettel Red Bull 1:50.814 +1.349 10 laps
14 Nico Hulkenberg Force India 1:50.866 +1.401 11 laps
15 Adrian Sutil Sauber 1:50.962 +1.497 12 laps
16 Romain Grosjean Lotus 1:51.509 +2.044 9 laps
17 Pastor Maldonado Lotus 1:51.610 +2.145 10 laps
18 Esteban Gutierrez Sauber 1:51.898 +2.433 15 laps
19 Jules Bianchi Marussia 1:52.457 +2.992 14 laps
20 Max Chilton Marussia 1:52.984 +3.519 14 laps
21 Marcus Ericsson Caterham 1:54.294 +4.829 11 laps
22 Andre Lotterer Caterham 1:55.008 +5.543 13 laps