Lewis Hamilton fastest in Spanish Grand Prix practice as Mercedes set the pace

Hamilton, searching for his second race win of the season, pipped his team-mate to the quickest lap time by just 0.029 seconds.

The Ferrari's of Kimi Raikkonen and Sebastian Vettel were best of the rest, a second behind their rivals.

The Mercedes duo clocked 58 laps between them in a smooth session for the world champion outfit, but it was not so positive for rival Ferrari and McLaren.

Championship leader Sebastian Vettel stopped at the exit of the pitlane, reporting an issue with the gearbox with just over an hour to go. After a short spell in the garage, the German rejoined the fray and ended up fourth quickest, just over a tenth adrift of his team-mate.

Fernando Alonso's session lasted just a handful of corners, his car snapping approaching Turn 3 with smoke and fluid pouring from his Honda power unit. Honda said it was an oil leak and in a bid to ensure he gets out for second practice, chose to change the engine while it investigated the problem. Alonso's team-mate Stoffel Vandoorne had a more fruitful session, recording 24 laps and the 12th quickest time.

Max Verstappen was the best of the Red Bulls in fifth, 1.185s off the pace and four tenths clear of team-mate Daniel Ricciardo.

Kevin Magnussen beat Romain Grosjean to seventh, but his session ended a few minutes early when he parked the Haas at the edge of the track at Turn 4.

Renault's Nico Hulkenberg and Toro Rosso's Carlos Sainz Jr completed the top 10.

Sergey Sirotkin, who took over Jolyon Palmer's Renault for this session, managed 10 laps and the 19th quickest time before his outing was curtailed by a water leak.

1. Lewis Hamilton (Britain) Mercedes 1:21.521

2. Valtteri Bottas (Finland) Mercedes 1:21.550

3. Kimi Raikkonen (Finland) Ferrari 1:22.456

4. Sebastian Vettel (Germany) Ferrari 1:22.600

5. Max Verstappen (Netherlands) Red Bull - TAG Heuer 1:22.706

6. Daniel Ricciardo (Australia) Red Bull - TAG Heuer 1:23.084

7. Kevin Magnussen (Denmark) Haas - Ferrari 1:23.670

8. Romain Grosjean (France) Haas - Ferrari 1:23.758

9. Nico Huelkenberg (Germany) Renault 1:23.993

10. Carlos Sainz Jr (Spain) Toro Rosso - Renault 1:24.004

11. Sergio Perez (Mexico) Force India - Mercedes 1:24.188

12. Esteban Ocon (France) Force India - Mercedes 1:24.324

13. Stoffel Vandoorne (Belgium) McLaren 1:24.400

14. Felipe Massa (Brazil) Williams-Mercedes 1:24.618

15. Daniil Kvyat (Russia) Toro Rosso - Renault 1:24.642

16. Marcus Ericsson (Sweden) Sauber - Ferrari 1:24.966

17. Pascal Wehrlein (Germany) Sauber - Ferrari 1:25.182

18. Lance Stroll (Canada) Williams-Mercedes 1:25.919

19. Sergey Sirotkin (Russia) Renault 1:26.293

20. Fernando Alonso (Spain) McLaren