Nico Rosberg posted the quickest time of the day at Catalunya to leave Williams on top of the pile after Friday practice for the Spanish Grand Prix.

Rosberg, who had been sixth quickest during the morning session, posted the fastest time in the second session to lead the way ahead of team-mate Kazuki Nakajima - with the pair running towards the head of the field throughout.

Rosberg eventually finished the session just over a tenth of a second clear of his Japanese team-mate despite his session ending with his car off the road after he developed mechanical issues in the closing minutes and was forced to pull off the circuit.

Nakajima in second, and third placed Fernando Alonso, both joined Rosberg in dipping below the morning time set by championship leader Jenson Button, who ended second free practice in sixth place. His morning time was good enough for the fourth quickest time overall.

FP2 saw Button outpaced by team-mate Rubens Barrichello in fourth, while the Red Bull of Mark Webber split the Brawn pairing in fifth.

Sebastian Vettel was seventh while Nelson Piquet was again inside the top eight despite sliding off into the gravel on new fewer than two occasions. Sebastien Buemi also ran into problems during the session after he stopped on track early on, but the Toro Rosso man recovered to take ninth place from Kimi Raikkonen's Ferrari.

Outside the top ten, Lewis Hamilton could manage only 13th, which was two places better than Felipe Massa's Ferrari. BMW Sauber and Toyota also found themselves towards the rear of the field as some teams turned focus towards preparing for Sunday's race as opposed to chasing a fast time.

Adrian Sutil failed to go out on track following a fuel cell issue and was the only man not to set a time.

To view second free practice times, CLICK HERE.

To view combined free practice times, CLICK HERE.