Belgian GP Practice One: Kimi Raikkonen ahead, Lewis Hamilton catches eye as F1 2017 restarts

Kimi Raikkonen set the pace for Ferrari in Practice One for the Belgian Grand Prix, but it was Lewis Hamilton's pace which caught the eye, as Formula 1 returned to action after its summer break.

Despite setting his best time on the slowest tyre compound available, the soft, Hamilton was just 0.053s adrift of pacesetter Raikkonen in second place despite the Ferrari running the fastest tyre on offer, the ultrasoft.

Championship leader Sebastian Vettel was 0.145s off the pace of his team-mate on the same ultrasoft tyres.

"It appears to be a massive first advantage to Mercedes, but it might not be as quite as clear as that," said Martin Brundle, who has returned to the Sky F1 team this weekend. "If those ultras are going off a bit at the end of that lap, you may be losing some of the advantage.

"Nonetheless, the lap times are super impressive - 2.8 seconds quicker than last year - and that is a great time on soft tyres."

There tends to be a difference in lap time between the ultrasoft and soft compound in excess of one second.

Red Bull also ran the purple-marked compound and although fourth and fifth, the RB13 was 0.8s adrift of Raikkonen around the fast, sweeping Spa-Francorchamps circuit.

Valtteri Bottas was a distant sixth on softs and damaged his Mercedes when he tagged the barriers after running into the gravel.

Meanwhile, Felipe Massa did more substantial damage to his Williams car after crashing heavily in the session's opening stages.

After being struck down by illness at the previous race in Hungary four weeks ago, Massa was passed fit to race by the FIA's doctors on Wednesday. However, the veteran's P1 session lasted barely a quarter of an hour after he ran off the circuit on his first flying lap at Malmedy.

There could be significant further repercussions for Massa and his Williams team too: technical chief Paddy Lowe admitted to Sky F1 the prospect of the Brazilian returning to the track in Practice Two "was a bit of a long shot" as the team now have to build up their spare chassis.

McLaren's Fernando Alonso, meanwhile, lost track time via an immediate problem with Honda's updated engine, before a DRS issue intervened. But team-mate Stoffel Vandoorne endured a smoother session and finished 10th, although the Belgian is braced for a 35-place grid penalty at his maiden home grand prix.

Britain's Jolyon Palmer enjoyed a solid start to his weekend by outpacing team-mate Nico Hulkenberg to finish as the lead Renault in 11th place.