SAKHIR, Bahrain -- Sebastian Vettel set the pace during a searing hot opening practice session at the Bahrain Grand Prix.
With qualifying and the race set to take place under floodlights, Friday's opening practice session in the heat of afternoon sun has little relevance in terms of track conditions for the rest of the weekend. As a result, Mercedes focused on wider development during the 90 minute session and did not set representative lap times on the soft tyres.
Vettel's Ferrari teammate Kimi Raikkonen suffered an engine failure after 37 minutes, meaning Vettel's fastest time of 1:32.697 had no real reference other than Red Bull's Daniel Ricciardo, who was 0.4s off in second. Max Verstappen was third fastest, a further 0.469s off his teammate in second, although both Red Bulls were faster in the first sector than Vettel's Ferrari.
Sergio Perez was fourth fastest for Force India ahead of the two Williamses of Felipe Massa and Lance Stroll. Massa's session ended 10 minutes early with an unusual incident at Turn 13 when his rear wheels locked unexpectedly and forced him into a spin. He held a 0.076s margin over teammate Stroll at the end of the session, who is hoping to be more competitive this weekend on a track where he has tested before. Esteban Ocon was seventh fastest in the second Force India, 0.237s off teammate Perez.
Fresh from announcing his decision to race at this year's Indy 500, Fernando Alonso was eighth fastest in the McLaren despite completing just 14 laps. Haas' Romain Grosjean was ninth, beating the fastest Mercedes of Lewis Hamilton in tenth. Daniil Kvyat was 11th fastest in the highest-placed Toro Rosso with Nico Hulkenberg 12th for Renault and Stoffel Vandoorne 13th after pulling to the side of the track with an engine issue after 10 laps.
Valtteri Bottas was 14th fastest in the second Mercedes -- over two seconds off Vettel -- and ahead of Jolyon Palmer in the second Renault, Kevin Magnussen in the second Haas and the two Saubers of Marcus Ericsson and Pascal Wehrlein. It was Wehrlein's first session back in the car since the second practice session in Australia -- after which he declared himself unfit to race at the first two rounds -- and he completed a total of 23 lap with a best time just 0.071s off teammate Ericsson. Carlos Sainz was 19th fastest ahead of Raikkonen in 20th, but spent the second half of the session on medium tyres and only completed 16 laps.