SPA-FRANCORCHAMPS, Belgium -- Ferrari's Kimi Raikkonen edged Lewis Hamilton by 0.053s to top the opening practice session for the Belgian Grand Prix.
The Finn, who this week was handed a contract extension into 2018, turned in a late 1:45.502 on the ultra-soft tyre to lead the session when the clock expired. Though it put him marginally ahead of Hamilton, the Mercedes driver set his quickest time on the soft tyre -- the hardest compound in Pirelli's range this weekend -- and still managed to split the best times Ferrari set on the ultra-soft, Pirelli's fastest tyre.
Hamilton spent much of the session on the soft tyre after running the latest Halo prototype early in the session. Though he did not post the quickest overall session time, Hamilton set the fastest time for each sector during different runs, suggesting he could have been ahead of Raikkonen with a clean lap. With qualifying simulations to come in the afternoon, it is unwise to read too much into the opening practice session of any F1 weekend, but the fact Mercedes already looks quick without having used the quickest tyre suggests pre-race predictions of the Spa-Francorchamps circuit suiting the world champions were correct.
The session was disrupted by a shunt for Williams' Felipe Massa, who was back in the car for the first time since skipping the Hungarian Grand Prix due to dizziness. The Brazilian driver, who was cleared to race by the medical team on Thursday, lost the rear of the car at Stavelot and went across the gravel and into the barrier, prompting a red flag. The contact damaged the left side of Massa's car and Williams later confirmed it would have to replace the Brazilian's chassis over lunch, making an appearance in FP2 uncertain.
Championship leader Sebastian Vettel finished third, 0.145s behind teammate Raikkonen, while Red Bull pair Max Verstappen and Daniel Ricciardo finished 0.7s behind. Though Red Bull's Renault power unit is likely to struggle to match Mercedes and Ferrari at Spa, the team will hope it can cut the gap over the two remaining practice sessions.
Valtteri Bottas finished sixth in the other Mercedes, 0.9s off the lead, in a session which saw him run wide at Turn 12 as he made way for a Force India and scrape the barriers. Though Bottas managed to get the car out of the gravel trap and return to the pits with minor front wing damage, the incident compromised the Finn's chance of matching any of the times set by the top three drivers.
Toro Rosso made an encouraging start to the weekend, with Carlos Sainz and Daniil Kvyat finishing either side of eighth-place Esteban Ocon. McLaren's Stoffel Vandoorne, who faces the prospect of a 35-place grid penalty for his first home race, rounded out the top ten, albeit 2.3s off the pace.
Renault pair Jolyon Palmer and Nico Hulkenberg finished 11th and 12th, split by just 0.1s, ahead of Fernando Alonso in the other McLaren. Alonso is running an upgraded Honda power unit this weekend but spent much of the session complaining that his Drag Reduction System (DRS) was not working throughout the lap.
Force India's Sergio Perez was 14th, ahead of Lance Stroll, who completed the bulk of Williams' 27 laps after Massa's early crash. Haas pair Kevin Magnussen and Romain Grosjean made a slow start to the weekend in 16th and 17th. Of the drivers who set a time, the Saubers finished last, with the disadvantage of its year-old Ferrari power unit already brutally exposed -- Marcus Ericsson finished 1.4s off Grosjean's best time. The gap to the front is likely to be less extreme once Sauber take on the ultra-soft tyre later in the weekend but the team is unlikely to occupy anything other than the bottom two positions of the timing screens.