Rosberg fastest in first Malaysia practice

The Williams drivers waited until the very last lap of the hot and humid 90 minutes to deny the Brawns of Jenson Button and Rubens Barrichello from continuing their dominance of Melbourne.

Ferrari's Felipe Massa and Kimi Raikkonen were fifth and sixth, but there was a late scare for the Finn when his cockpit extinguisher fired halfway down the back-straight - it is not known whether this was related to the car's KERS system or not.

As in Australia, there was a lull of 20 minutes before anyone bothered to start lapping sensibly.

But when they did, it was Raikkonen that got the ball rolling, running timed laps immediately after his installation lap.

The Finn's initial mark was almost immediately eclipsed by Nakajima's Williams, and the two traded times at the top until Massa beat them both with a 1:37.343 after 40 minutes.

Not wishing to miss out, Rosberg, the star of Melbourne free practice, immediately replaced Massa at the top, but by this stage Button was out on track and hunting down the German's time.

Button's first attempt was 0.16 seconds shy of Rosberg, but by the hour mark he was on top with a lap of 1:36.676. He improved that to a 1:36.430, which looked good enough to give him the top spot until Williams denied him late-on.

Behind the Brawns, Williams and Ferraris is Lewis Hamilton in seventh, having enjoyed a reasonably competitive session, less than half a second away from the ultimate pace - although both he and McLaren team-mate Heikki Kovalainen ended the session in the pits with their cars being worked on.

The Finn in particular only completed seven laps and ended the session at the bottom of the timesheet.

Mark Webber and Sebastian Vettel were eighth and ninth for Red Bull, followed by the Toyotas of Timo Glock and Jarno Trulli. Giancarlo Fisichella put in a feisty performance to go 12th.

There was plenty of incident as well. Other than Raikkonen's dramas, Nelson Piquet spun into the gravel at Turn 6 when something appeared to fall off the front of his Renault car.

Trulli, Fisichella, Robert Kubica, Glock, Sebastien Bourdais, Massa, Hamilton and Fernando Alonso all either had spins or off-track excursions.

Pos  Driver        Team                      Time              Laps
 1.  Rosberg       Williams-Toyota      (B)  1:36.260           27
 2.  Nakajima      Williams-Toyota      (B)  1:36.305 + 0.045   25
 3.  Button        Brawn GP-Mercedes    (B)  1:36.430 + 0.170   20
 4.  Barrichello   Brawn GP-Mercedes    (B)  1:36.487 + 0.227   22
 5.  Massa         Ferrari              (B)  1:36.561 + 0.301   21
 6.  Raikkonen     Ferrari              (B)  1:36.646 + 0.386   18
 7.  Hamilton      McLaren-Mercedes     (B)  1:36.699 + 0.439   16
 8.  Webber        Red Bull-Renault     (B)  1:36.703 + 0.443   23
 9.  Vettel        Red Bull-Renault     (B)  1:36.747 + 0.487   25
10.  Glock         Toyota               (B)  1:36.980 + 0.720   27
11.  Trulli        Toyota               (B)  1:36.982 + 0.722   26
12.  Fisichella    Force India-Mercedes (B)  1:37.025 + 0.765   20
13.  Kubica        BMW Sauber           (B)  1:37.039 + 0.779   18
14.  Piquet        Renault              (B)  1:37.199 + 0.939   20
15.  Sutil         Force India-Mercedes (B)  1:37.241 + 0.981   18
16.  Alonso        Renault              (B)  1:37.395 + 1.135   12
17.  Buemi         Toro Rosso-Ferrari   (B)  1:37.634 + 1.374   22
18.  Heidfeld      BMW Sauber           (B)  1:37.640 + 1.380   17
19.  Bourdais      Toro Rosso-Ferrari   (B)  1:38.022 + 1.762   19
20.  Kovalainen    McLaren-Mercedes     (B)  1:38.483 + 2.223    7

All timing unofficial