Ferrari topped the timesheets in a blisteringly-hot first practice session at the Bahrain Grand Prix, with Kimi Raikkonen leading Sebastian Vettel by 0.202s while Mercedes focused on longer, slower runs.

Bahrain Grand Prix - FP1 Time (Laps) 1. RAI Ferrari 1:37.827 (13) 2. VET Ferrari 1:38.029 (12) 3. BOT Williams 1:39.390 (23) 4. SAI Toro Rosso 1:38.477 (14) 5. RIC Red Bull 1:38.455 (17) 6. VES Toro Rosso 1:38.504 (22) 7. ALO McLaren 1:38.598 (18) 8. NAS Sauber 1:38.628 (17) 9. KVY Red Bull 1:38.661 (17) 10. MAS Williams 1:38.790 (21) 11. PER Force India 1:38.793 (15) 12. MAL Lotus 1:38.842 (23) 13. HUL Force India 1:39.187 (20) 14. PAL Lotus 1:39.283 (31) 15. ROS Mercedes 1:39.293 (23) 16. HAM Mercedes 1:39.532 (22) 17. ERI Sauber 1:39.534 (21) 18. STE Manor 1:42.973 (12) 19. MER Manor 1:43.265 (15) 20. BUT McLaren No time (2)

The session, which took part in 35C heat, is not representative of either qualifying or the race, which are both run in cooler conditions after sunset. As a result run plans seemed to vary up and down the pit lane and quick laps came at seemingly random intervals throughout the session.

For a while Fernando Alonso led the way in the McLaren before being usurped by Valtteri Bottas and then the two Ferraris in the final ten minutes. Mercedes, meanwhile, pounded round with heavy fuel and completed 45 laps between the two cars.

Ferrari did not have it all its own way as Vettel appeared to be down on power on one of his early runs and returned to the pits for the best part of an hour before re-emerging and setting his quick lap. It's unlikely it held back his preparations too much as he only completed one lap less than team-mate Raikkonen and set a quick time regardless.

Jenson Button experienced a far more serious problem when his McLaren cut out with an electrical issues and spun on his first flying lap of the circuit. The rear-end stepped out and the MP4-30 was left stranded in the middle of the corner without power. He missed out on the rest of the session and will be hoping the problem can be diagnosed and fixed before FP2 in the evening, which is the only practice session run in conditions comparable with qualifying and the race. Alonso managed 18 laps in the sister McLaren, but was clearly struggling under braking for Turn 1 as he set the seventh fastest time.

Even though the times are unlikely to representative of qualifying, the top 11 were separated by less than a second, which bodes well for a competitive weekend in the midfield. The Manors took up residence in their usual section of the timesheets with Will Stevens 5.1s off the pace and Roberto Merhi 6.4 shy of the Ferraris.