Belgian F1 GP: Lewis Hamilton heads practice three for Mercedes

The reigning F1 world champion clocked a 1m48.984s to finished 0.498 seconds quicker than his title rival, who was fastest in both practice sessions on Friday.

Ferrari proved to be Mercedes' closest challenger at a gloriously sunny Spa Francorchamps, with Sebastian Vettel third and his team-mate Kimi Raikkonen fourth.

Sergio Perez set the fastest final sector as he ended up fifth, two tenths and three places clear of team-mate Nico Hulkenberg to suggest Force India can aim for the final part of qualifying later on Saturday.

The Red Bull drivers and Toro Rosso's Max Verstappen, who will start towards the back of the grid because of a 10-place grid penalty for an engine change, completed their soft tyre qualifying-simulations early in the session.

That allowed them to spend the rest of the session to gathering long-run data, making up for the red flag disruptions in Friday's second practice.

Daniel Ricciardo was sixth quickest, 0.050s ahead of Red Bull team-mate Daniil Kvyat, with Verstappen 13th overall.

The Williams of Valtteri Bottas and Felipe Massa completed the top 10 ahead of Toro Rosso's Carlos Sainz Jr in 11th and Lotus's Pastor Maldonado in 12th.

It was a difficult day for McLaren-Honda, whose cars are already destined to stat at the back of the grid following a host of engine penalties.

Fernando Alonso managed just a single installation lap before returning to the garage.

The team stripped down the car in a bid to get to the root of the problem, which chief operating officer Jonathan Neale suggested could be an exhaust gas leak, and failed to get him back out..

His team-mate Jenson Button managed more running, completing 12 laps, but finished 17th, 2.997s off the pace.

Sauber, which has the 2015-spec Ferrari engine for the first time this season, was quick on Friday, but Felipe Nasr and Marcus Ericsson failed to repeat that form, ending practice three 14th and 15th respectively.

Romain Grosjean was 16th quickest, but complained to his team on the radio that he was baulked badly by Raikkonen, who was cruising slowly back to the pits.

Following Rosberg's rear tyre failure at high speed in second practice, which Pirelli determined not to be a structural integrity issue, final practice passed without further incident.

PRACTICE THREE TIMES: