Nico Rosberg rediscovered his early weekend form in time to post the fastest time of all in the opening practice session for this weekend's Malaysian Grand Prix.

Having paced all three free sessions in Melbourne a week ago, the Williams driver was a feature towards the top of the timesheets throughout the 90-minute outing, before vaulting ahead of Australian GP winner Jenson Button with a last-ditch lap.

The German, who admitted that he was disappointed to only qualifying fifth at Albert Park - and even more disappointed to fail to capitalise on that in the opening race of the year - posted a 1min 36.260secs benchmark after overhauling Button's late session time, while Williams team-mate Kazuki Nakajima followed Rosberg over the line to also displace the current championship leader.

The diffuser teams continued to rule the roost as Brawn GP claimed third and fourth on the timesheets, Button being pushed back into tandem with team-mate Rubens Barrichello after his own final lap - sandwiched between the Williams duo on track - failed to improve on his 1min 36.305secs best.

Nakajima finished the session just 0.045secs shy of Rosberg, with Button 0.170secs off the best. Once again, however, the new rules appeared to have produced a close-fought session, with the top 15 - stretching down to Force India's Adrian Sutil - all within a second of the pace.

Ferrari pair Felipe Massa and Kimi Raikkonen finished fifth and sixth, just ahead of Lewis Hamilton, who shrugged aside the drama of Thursday to post an improved seventh-best time for McLaren. Red Bull twins Mark Webber and Sebastian Vettel, and Toyota's Timo Glock rounded out the top ten.

Although the session may have opened quietly, however, there was no shortage of incident in the closing moments, with Raikkonen the main frontrunner to be affected. The Finn was out in search of an improvement when smoke started pouring from both under the engine cover and out of the cockpit. Struggling to see, Raikkonen raised himself in the cockpit and managed to get the F60 back to the pits, but his reaction - and those of the Ferrari team - suggested a problem with its KERS system.

Elsewhere, there were the usual off-track excursions as drivers explored the limits of their cars on the Sepang circuit, but none more dramatic than Nelson Piquet Jr's. The Brazilian appeared to suffer a failure in the front right corner of his Renault, maybe a puncture or suspension failure, that saw him run straight over the chicane and deep into the gravel.

As the second year driver climbed out, team-mate Fernando Alonso ran through the gravel further around the circuit, but managed to find the grass fringe and resumed. Raikkonen, both Toyotas and Force India's Giancarlo Fisichella all also suffered notable moments, while BMW duo Robert Kubica and Nick Heidfeld, Toro Rosso's Sebastien Bourdais and Heikki Kovalainen all reported ailments as they struggled to get off the bottom of the timesheets. Indeed, the Finn ended the session with his car up on stands and various parts being removed in search of a cure....