Hamilton leads opening Sepang practice

After a low-key opening to the morning, with the small teams monopolising the early track time, McLaren's Hamilton and Jenson Button moved into first and second around the session's halfway mark, before - like most of its rivals - focusing on heavier fuel runs later in the morning.

Their positions looked set going into the closing moments, until Rosberg slipped through with a lap 0.185 seconds off Hamilton's pace just after the chequered flag to split the McLarens.

Michael Schumacher was fourth in the second Mercedes. The former champion did not set a flying lap at all until just over the one hour mark while Mercedes worked on the rear of his car, but once on track Schumacher was rapid and quickly worked his way up to third, which became fourth when Rosberg jumped up the order.

Renault's Robert Kubica briefly led the way prior to the McLarens' mid-session surge and ended up fifth, ahead of Red Bull's Mark Webber, Force India's Adrian Sutil, and championship leader Fernando Alonso (Ferrari) in eighth.

Sebastian Vettel was only ninth for Red Bull, and at one stage reported issues with slowing the car down. But he did set the fastest sector two time of the morning on his in-lap after the flag. Sebastien Buemi completed the top ten for Toro Rosso.

Felipe Massa made two trips through the gravel and was 11th for Ferrari. Also in trouble were Toro Rosso's Jaime Alguersuari, who lost time to an electrical problem but recovered to 13th after repairs, and Sauber's Pedro de la Rosa. Like Massa, the Spaniard skittered through the Turn 12 gravel at speed but rejoined without damage.

Lotus test driver Fairuz Fauzy did a solid job on his first appearance in a GP weekend session. The Malaysian had a half-spin and brief trip over the grass, but was within half a second of team-mate Jarno Trulli until the Italian improved late on, and ultimately took 22nd. Force India's Paul di Resta, the other reserve driver in action, was 15th.

Pos  Driver         Team                    Time               Laps
 1.  Hamilton       McLaren-Mercedes        1:34.921  		19 
 2.  Rosberg        Mercedes                1:35.106  + 0.185   19
 3.  Button         McLaren-Mercedes        1:35.207  + 0.286   25
 4.  Schumacher     Mercedes                1:35.225  + 0.304   14
 5.  Kubica         Renault                 1:35.402  + 0.481   22
 6.  Webber         Red Bull-Renault        1:35.479  + 0.558   22
 7.  Sutil          Force India-Mercedes    1:35.955  + 1.034   20 
 8.  Alonso         Ferrari                 1:35.959  + 1.038   20
 9.  Vettel         Red Bull-Renault        1:35.043  + 1.122   19
10.  Buemi          Toro Rosso-Ferrari      1:36.100  + 1.179   20
11.  Massa          Ferrari                 1:36.451  + 1.530   22
12.  Kobayashi      Sauber-Ferrari          1:36.503  + 1.582   28
13.  Alguersuari    Toro Rosso-Ferrari      1:36.645  + 1.724   18
14.  Petrov         Renault                 1:36.712  + 1.791    9
15.  di Resta       Force India-Mercedes    1:36.891  + 1.970   25
16.  de la Rosa     Sauber-Ferrari          1:36.899  + 1.978   24
17.  Hulkenberg     Williams-Cosworth       1:37.802  + 2.881   27
18.  Barrichello    Williams-Cosworth       1:38.278  + 3.357   18
19.  Trulli         Lotus-Cosworth          1:39.460  + 4.539   21
20.  Glock          Virgin-Cosworth         1:39.755  + 4.834   17
21.  di Grassi      Virgin-Cosworth         1:40.159  + 5.238   25
22.  Fauzy          Lotus-Cosworth          1:40.721  + 5.800   19
23.  Senna          HRT-Cosworth            1:41.832  + 6.911   27
24.  Chandhok       HRT-Cosworth            1:41.966  + 7.045   24

All Timing Unofficial