Lewis Hamilton continued to set the pace on the opening day of the Malaysian Grand Prix, returning to the top of the timesheets in the late afternoon session as the forecast rain held off at Sepang.
The FP1 pacesetter was quickly back at the top of the timesheets, as drivers took heed of the shower warning by heading out early in the 90-minutes session, but, even though Hamilton's initial benchmark was only nine-tenths off his previous best, it was equally quickly usurped by Daniel Ricciardo and Toro Rosso. The Australian enjoyed his own brief spell in top spot before Hamilton returned to claim the mantle of pacesetter, only for Michael Schumacher to trim another tenth from the target. Not to be outdone, however, Hamilton was back in P1 before the chequered flag fell, although his 1min 38.172secs best came up just short of beating his earlier 1min 38.021secs.
Almost every driver found that the Pirelli compounds on offer degraded more rapidly than they did a week ago in Australia, as the sweltering temperatures softened the rubber and left cars sliding wildly.
Schumacher remained second in the session, and on the combined timesheets as the field was almost equally split between those setting their best marks in the first and second sessions.
Reigning world champion Sebastian Vettel was firmly in the former camp, his second session best being almost a second slower, but the Red Bull driver held on to third overall for the day, even though Australian GP winner Jenson Button matched his effort to the thousandth as he bounced back from the oil leak that curtailed his earlier effort. Just two-thousandths split Schumacher in P2 from the two men behind him, while Mercedes team-mate Nico Rosberg was just a tenth further back as the W03 again showed its potential.
Ricciardo ended the day in an impressive sixth place as STR upped its pace after the afternoon break, while team-mate Jean-Eric Vergne again just missing out on a top ten spot. Ricciardo just edged out Ferrari's Fernando Alonso, again doing a superior job to team-mate Felipe Massa when turning up the wick was required, while Romain Grosjean, Mark Webber and Kimi Raikkonen rounded out the top day on the combined timesheets, despite the Finn only posting the 15th best effort in the later session.
Paul di Resta finished the day in the top half of the timesheet despite a fraught session that included a brake fire and a grassy off as the result of trying too hard for an improvement. Force India team-mate Nico Hulkenberg was one place further back after lapping just over a tenth of a second slower.
Pastor Maldonado improved enough in the second session to move above Williams reserve Valtteri Bottas, while Bruno Senna was unable to better 19th overall after taking over from the Finn in the later outing. That left the Brazilian behind both Massa and Heikki Kovalainen on the combined times, although the Caterham driver was another to have his session cut short when development parts fitted to his T128 failed to yield the desired effect.
The Finn still lapped half a second quicker than team-mate Vitaly Petrov as the pair sandwiched Senna. Both also ended the day ahead of a troubled Sergio Perez, who improved his time, but not his position, in the second session.
Although Sauber team-mate Kamui Kobayashi suffered a gearbox problem similar to his in Melbourne, the Mexican would have been relieved, therefore, to remain ahead of the two Marussia drivers who, like their counterparts at HRT, both improved their efforts as the day went on. Timo Glock also bettered Kovalainen in the second session, but remained behind the Finn on the combined timesheet. The German bettered rookie team-mate Charles Pic by over a second, while the lead HRT, of Narain Karthikeyan, got to within eight-tenths of the Frenchman by the time the flag fell.