Lewis Hamilton finished the first practice session for the Spanish Grand Prix on top as he showed no signs of slowing since his last victory three weeks ago.
Hamilton was 0.868s quicker than Jenson Button, who was top of the timesheets until the final ten minutes of the session, while Mercedes team-mate Nico Rosberg was limited to just nine laps and was fifth fastest. Rosberg spent most of the session watching on as mechanics worked on his car, which was suffering with an ERS cooling problem, and he will be frustrated after hoping for a clean weekend to regain momentum in his battle with Hamilton in the drivers' championship.
Daniel Ricciado was third fastest and the only Red Bull driver to set a competitive time after Sebastian Vettel came to a halt early in the session. Vettel had completed just four laps when his Red Bull stopped at Turn 6 with a suspected electrical issue and he remained with the car, armed with a fire extinguisher, as it was lifted onto the back of a truck. Fernando Alonso was fourth fastest and 1.105s off the pace of Hamilton, while Ferrari team-mate Kimi Raikkonen was another couple of tenths off in sixth.
Giedo van der Garde, who was driving Esteban Gutierrez's Sauber in FP1, came close to a big accident at Turn 1 when his brakes seemed to play up at the fastest part of the circuit. He did well to keep the car out of the barriers as he shot through the corner with one wheel locked up and sent the photographers on the outside of the track running for cover. He managed to get the car back to the pits and returned to the track before the end of the session.
The session featured another couple of bizarre incidents, with a mirror falling off the Force India of Sergio Perez and into the cockpit, where he held it while driving one-handed back to the pits. Ricciardo also appeared to lose something from around the cockpit of his Red Bull in the final sequence of corners but a quick visit to the pits remedied any issue and he was sent back on track.
Pastor Maldonado showed some promising pace in the upgraded Lotus, with the eighth fastest time and an impressive 34 laps in total. Perez and Felipe Massa ensured Force India and Williams remained in the top ten, but both teams could be a little bit further off the pace than in recent races due to the characteristics of the circuit.