Sauber's Esteban Gutierrez suffers a suspected gearbox issue © FOWC Ltd. No reproduction without permission.
Lewis Hamilton had set the pace for Mercedes while teams were running the medium compound Pirelli, but as he made mistakes on his laps on the soft tyre, Rosberg kept his cool and jumped to the top with 1m 29.375s. As Hamilton failed to improve on his medium-tyre time of 1m 30.919s and thus finished fourth, Button jumped up to second on 1m 30.766s chased by Fernando Alonso's Ferrari on 1m 30.876s.
Daniel Ricciardo got beneath 1m 31s, with 1m 30.970s for Red Bull, which left them 1.595s off Mercedes' pace, but as the home favourite made the most of what he had, team mate Sebastian Vettel was in a world of hurt down in 12th place on 1m 32.255s after sliding all over the place on his soft-tyre run. He complained later that his car wasn't accelerating properly too.
Between the two RB10 pilots, Nico Hulkenberg jumped up to sixth late on with 1m 30.978s for Force India, displacing Kimi Raikkonen on 1m 31.156s for Ferrari and Kevin Magnussen on 1m 31.251s in the other McLaren. Sergio Perez had a couple of offs in the other Force India on his way to 1m 31.665s which left him ahead of a disappointed Felipe Massa on 1m 31.723s. The Brazilian failed to improve that time, which was set on the medium tyre and had been third fastest behind the Mercedes in comparable conditions, when he switched his Williams to softs. But at least he ran; team mate Valtteri Bottas didn't record a time after spending the session with his FW36 in the garage having its gearbox changed.
Daniil Kvyat added to Vettel's pain by slipping ahead of him with 1m 31.925s for Toro Rosso, while team mate Jean-Eric Vergne was right behind the champion on 1m 32.417s in the sister STR9.
Marussia were chuffed with Jules Bianchi's 14th best time of 1m 34.184s, which put the Frenchman ahead of troubled Adrian Sutil who said his Sauber was all over the place as he struggled to 1m 34.188s.
It was a vastly better day for Caterham and Kamui Kobayashi wound up his CT05 for the first time to take a promising 16th on 1m 34.413s, only three tenths off Bianchi. Behind the Japanese driver Max Chilton took his Marussia round in 1m 34.717s for 17th from Pastor Maldonado's Lotus on 1m 34.754s and Marcus Ericsson who worked down to 1m 36.159s in his Caterham.
Besides Bottas, Esteban Gutierrez didn't set a time after running into gearbox problems at the start of the session in his Sauber. Romain Grosjean was also in the wars, getting increasingly vexed by an ongoing misfire. With Maldonado stopping the other E22 right at the end, Lotus's woes continued.
The scene is thus set for a great first qualifying session of the season.