Lewis Hamilton has shown his intent as he tries to clinch his fourth victory this season by finishing fastest in the first practice session ahead of the Spanish Grand Prix.
Last season's champion Sebastian Vettel suggested this week that Red Bull need to top the podium in Barcelona in order to chase down Mercedes in the table.
However, it was a poor start for the German, whose car rolled to a halt at turn five, forcing Vettel to retire due to an electrical fault.
His teammate Daniel Ricciardo fared better as he clocked the third-quickest time on the track, while Jenson Button led the way for McLaren for the majority of the session until Hamilton moved on top.
The Brit's Mercedes teammate Nico Rosberg finished fifth in the standings, while Fernando Alonso clocked the fourth-quickest time for Ferrari in his homeland.
Full standings:
1. Lewis Hamilton (Mercedes)
2. Jenson Button (McLaren)
3. Daniel Ricciardo (Red Bull)
4. Fernando Alonso (Ferrari)
5. Nico Rosberg (Mercedes)
6. Kimi Raikkonen (Ferrari)
7. Kevin Magnussen (McLaren)
8. Pastor Maldonado (Lotus)
9. Sergio Perez (Force India)
10. Felipe Massa (Williams)
11. Daniil Kvyat (Toro Rosso)
12. Nico Hulkenberg (Force India)
13. Jean-Eric Vergne (Toro Rosso)
14. Felipe Nasr (Williams)
15. Adrian Sutil (Sauber)
16. Jules Bianchi (Marussia)
17. Romain Grosjean (Lotus)
18. Giedo van der Garde (Sauber)
19. Max Chilton (Marussia)
20. Sebastian Vettel (Red Bull)
21. Kamui Kobayashi (Caterham)
22. Marcus Ericsson (Caterham)
