Belgian GP: Nico Rosberg quickest in opening practice session

As expected, Mercedes­-engined cars dominated the top 10, with the 'works' cars trading quickest times in the final half hour.

Rosberg topped the timesheets for the first half of the session with a 1m51.724s lap before Hamilton edged ahead, but Rosberg hit back by going another tenth of a second faster.

Hamilton's race engineer Peter Bonnington informed him that the time came from Rosberg being quicker through the chicane and picking up more mid­-corner ­to ­exit speed at Pouhon.

Both Mercedes then returned to the circuit in the final minutes but did not improve their times.

Ferrari arrived at Spa with a revised low­-downforce aero package and proved to be the fastest non­-Mercedes team. Fernando Alonso was especially impressive, third fastest and just two tenths off Rosberg's benchmark.

Kimi Raikkonen, so often a Spa specialist, continued to fight his F14 T but finished fifth fastest, albeit a second slower than his team-­mate.

The Ferraris sandwiched the McLaren of fourth-­placed Jenson Button, who survived a brief scare when his DRS stuck open. Button was a comfortable half­ second faster than team-­mate Kevin Magnussen.

Red Bull's Daniel Ricciardo was the only other top 10 runner without a Mercedes engine, closing the session in ninth place, behind Magnussen and the two Force Indias of Sergio Perez and Nico Hulkenberg.

Ricciardo's team-­mate Sebastian Vettel was two places adrift after an eventful session. He reported gearshift problems and ran off ­track at Pouhon, then ran just another handful of laps before returning to the garage with a temperature-­related exhaust failure.

Valtteri Bottas was the only Williams driver to finish inside the top 10, seven tenths quicker than team-­mate Felipe Massa.

While 1.595s separated P1 from P10, the gap from fastest to slowest on the entire grid was a substantial 6.4s, with the usual suspects propping up the order.

Alexander Rossi, who will not now drive in the grand prix, was over a second slower than Marussia team-­mate Jules Bianchi.

It only took F1 debutant Andre Lotterer 10 laps at the wheel of the newly upgraded Caterham to overhaul team-­mate Marcus Ericsson, who spun at La Source in response.

Pos Driver               Team                  Time       Gap     Laps
 1. Nico Rosberg         Mercedes              1m51.577s           25 
 2. Lewis Hamilton       Mercedes              1m51.674s  +0.097s  24 
 3. Fernando Alonso      Ferrari               1m51.805s  +0.228s  16 
 4. Jenson Button        McLaren-Mercedes      1m52.404s  +0.827s  21 
 5. Kimi Raikkonen       Ferrari               1m52.818s  +1.241s  17 
 6. Sergio Perez         Force India-Mercedes  1m52.903s  +1.326s  24 
 7. Kevin Magnussen      McLaren-Mercedes      1m52.922s  +1.345s  23 
 8. Nico Hulkenberg      Force India-Mercedes  1m52.937s  +1.360s  22 
 9. Daniel Ricciardo     Red Bull-Renault      1m52.972s  +1.395s  19 
10. Valtteri Bottas      Williams-Mercedes     1m53.172s  +1.595s  20 
11. Sebastian Vettel     Red Bull-Renault      1m53.369s  +1.792s  11 
12. Daniil Kvyat         Toro Rosso-Renault    1m53.594s  +2.017s  21 
13. Romain Grosjean      Lotus-Renault         1m53.597s  +2.020s  20 
14. Adrian Sutil         Sauber-Ferrari        1m53.703s  +2.126s  14 
15. Felipe Massa         Williams-Mercedes     1m53.968s  +2.391s  20 
16. Jean-Eric Vergne     Toro Rosso-Renault    1m54.189s  +2.612s  20 
17. Giedo van der Garde  Sauber-Ferrari        1m54.335s  +2.758s  16 
18. Pastor Maldonado     Lotus-Renault         1m55.336s  +3.759s  21 
19. Jules Bianchi        Marussia-Ferrari      1m55.782s  +4.205s  19 
20. Alexander Rossi      Marussia-Ferrari      1m57.232s  +5.655s  20 
21. Andre Lotterer       Caterham-Renault      1m57.886s  +6.309s  24 
22. Marcus Ericsson      Caterham-Renault      1m57.977s  +6.400s  24