Kimi Raikkonen and Sebastian Vettel boosted Ferrari ahead of qualifying by posting the fastest times in final free practice session of the Belgian Grand Prix weekend.
Raikkonen, fastest in Friday's first practice, set a best time of 1:43.916 which was 0.197 of a second faster than championship leader Vettel and two tenths up on Mercedes driver Lewis Hamilton.
Hamilton, fastest in second practice ahead of Raikkonen, will hope to find extra speed in qualifying. The British driver is looking to equal Michael Schumacher's pole position record of 68.
Red Bull's Max Verstappen was fourth, ahead of Valtteri Bottas' Mercedes and Daniel Ricciardo in the other Red Bull fifth - the three separated by a couple of tenths - however the trio were over a second down on the benchmark times.
Jolyon Palmer caused a surprise by ending the session seventh in the Renault, and in a rare occasion ending the one hour session faster than his teammate Nico Hulkenberg who was only good for 11th.
Force India's Sergio Perez got the better of Esteban Ocon for the first time this weekend, ending eighth on the timing screens with the young Frenchman down in 12th.
Carlos Sainz was ninth in the Toro Rosso, with McLaren's Fernando Alonso rounding out the top ten.
Third practice was briefly interrupted when Daniil Kvyat pulled up at the top of the daunting Raidillon climb with signs of fire at the back of his Toro Rosso.
Felipe Massa was back in action after crashing his Williams early in FP1 and missing FP2 altogether on Friday. he was 16th, behind rookie teammate Lance Stroll in 15th.
Mercedes chief and triple F1 World Champion Niki Lauda summed up: "Ferrari's competitive but let's wait and see for qualifying – it's going to be very close today."
"Normally we're a little bit ahead, and now Ferrari's ahead. Everyone can find a little bit of engine speed but, unfortunately, I think Ferrari can find the same engine speed as Mercedes can," added Lauda.