Lewis Hamilton continued McLaren's strong form by setting the fastest time in the opening free practice session ahead of the Malaysian Grand Prix at Sepang.

Lewis Hamilton continued McLaren's strong form by setting the fastest time in the opening free practice session ahead of the Malaysian Grand Prix at Sepang.

The Briton topped the morning by half a second over world champion Sebastian Vettel's Red Bull, with the two Mercedes next up. Melbourne winner Jenson Button was hampered by an oil leak and was back in ninth for McLaren.

Although forecasts of rain later encouraged teams to complete plenty of mileage this morning, it was still half an hour into the session before serious times were set, with Kimi Raikkonen and Michael Schumacher leading briefly for Lotus and Mercedes respectively before Hamilton and Vettel began a battle for first place.

A 1m38.598s put the McLaren in front after 34 minutes, but only for two minutes before Vettel beat it by 0.063 seconds.

Hamilton narrowly missed out on reclaimed first place with his next lap, before putting in the 1m38.021s that would keep him ahead for the rest of the session.

Behind Vettel, Nico Rosberg narrowly beat Mercedes team-mate Schumacher to third.

Romain Grosjean took fifth for Lotus despite pitting for checks early on after reporting a strange feeling at the rear of the car.

Mark Webber completed the top six in the second Red Bull, ahead of Raikkonen, with Paul di Resta and Nico Hulkenberg's Force Indias eighth and 10th.

Button managed to complete 15 laps before the issue that left his McLaren parked in the garage for the final part of the session.

Williams test driver Valtteri Bottas made his debut in an official session with 11th place, 0.059s quicker than team-mate Pastor Maldonado.

Ferrari was back in 13th and 15th with Felipe Massa and Fernando Alonso.

Problems continued for HRT, as Narain Kartikeyan parked on track with gearbox issues after eight laps, and Pedro de la Rosa was 7.5s off the pace at the back of the pack.

Pos  Driver                Team                   Time               Laps
 1.  Lewis Hamilton        McLaren-Mercedes       1m38.021s            19
 2.  Sebastian Vettel      Red Bull-Renault       1m38.535s  + 0.514   21
 3.  Nico Rosberg          Mercedes               1m38.813s  + 0.792   21
 4.  Michael Schumacher    Mercedes               1m38.826s  + 0.805   19
 5.  Romain Grosjean       Lotus-Renault          1m38.919s  + 0.898   17
 6.  Mark Webber           Red Bull-Renault       1m39.092s  + 1.071   20
 7.  Kimi Raikkonen        Lotus-Renault          1m39.128s  + 1.107   22
 8.  Paul di Resta         Force India-Mercedes   1m39.298s  + 1.277   23
 9.  Jenson Button         McLaren-Mercedes       1m39.323s  + 1.302   15
10.  Nico Hulkenberg       Force India-Mercedes   1m39.440s  + 1.419   19
11.  Valterri Bottas       Williams-Renault       1m39.724s  + 1.703   23
12.  Pastor Maldonado      Williams-Renault       1m39.783s  + 1.762   23
13.  Felipe Massa          Ferrari                1m39.896s  + 1.875   16
14.  Kamui Kobayashi       Sauber-Ferrari         1m39.910s  + 1.889   21
15.  Fernando Alonso       Ferrari                1m39.980s  + 1.959   23
16.  Jean-Eric Vergne      Toro Rosso-Ferrari     1m40.099s  + 2.078   23
17.  Heikki Kovalainen     Caterham-Renault       1m40.247s  + 2.226   19
18.  Daniel Ricciardo      Toro Rosso-Ferrari     1m40.469s  + 2.448   23
19.  Vitaly Petrov         Caterham-Renault       1m40.857s  + 2.836   25
20.  Sergio Perez          Sauber-Ferrari         1m41.085s  + 3.064   23
21.  Timo Glock            Marussia-Cosworth      1m43.170s  + 5.149   18
22.  Charles Pic           Marussia-Cosworth      1m44.580s  + 6.559   14
23.  Narain Karthikeyan    HRT-Cosworth           1m45.360s  + 7.339    8
24.  Pedro de la Rosa      HRT-Cosworth           1m45.528s  + 7.507   18

All Timing Unofficial