Lewis Hamilton went quickest in the opening practice session ahead of Sunday’s Malaysian Grand Prix, the Mercedes driver finishing ahead of Ferrari’s Kimi Raikkonen and the second Mercedes of Nico Rosberg.

Hamilton’s timesheet-topping lap came roughly an hour into the session his time of 1:40.691 being good enough to see off Raikkonen, who finished 0.152s down on the Briton. Raikkonen, who looked to have overcome some of the handling problems that hampered his race weekend in Melbourne two weeks again, finished three tenths of a second clear of Rosberg.

Early in the session Rosberg had a nervous moment, locking up on entry into the pitlane and lack of grip on the dirty and dusty track was a problem for many during the session, including Ferrari’s Fernando Alonso, who spun in Turn 8 and Hamilton, who went off at Turn 11 in the session’s closing stages.

The high heat and humidity in Sepang had been predicted to cause problems for F1’s power units and a number of team’s encountered reliability problems in the morning session.

Kevin Magnussen lost power in his McLaren at the pitlane entrance, while Lotus again suffered major problems, with Romain Grosjean stopping on track after just two laps with a problem with his MGU-H. Team-mate Pastor Maldonado, meanwhile, spent most of the session in the garage and then on his first lap out his Lotus expired in a pall of smoke. Sergio Perez too hit trouble, the Force India driver completing just an installation lap during the session.

With Rosberg third, the morning’s fourth-fastest time went to McLaren’s Jenson Button, with team-matre Magnussen fifth. Toro Rosso’s Jean-Eric Vergne was sixth with a lap seven tenths off Hamilton’s pace. World champion Sebastian Vettel finish in seventh place, a futher tenth of a second back. The top ten order was rounded out by Force India’s Nico Hulkenberg and the Williams pairing of Felipe Massa and Valtteri Bottas.

2014 Malaysian Grand Prix – Free Practice 1 Result
1 Lewis Hamilton Mercedes 1:40.691 19 laps
2 Kimi Räikkönen Ferrari 1:40.843 0.152 20 laps
3 Nico Rosberg Mercedes 1:41.028 0.337 19 laps
4 Jenson Button McLaren 1:41.111 0.420 20 laps
5 Kevin Magnussen McLaren 1:41.274 0.583 18 laps
6 Jean-Eric Vergne Toro Rosso 1:41.402 0.711 15 laps
7 Sebastian Vettel Red Bull Racing 1:41.523 0.832 9 laps
8 Nico Hulkenberg Force India 1:41.642 0.951 19 laps
9 Felipe Massa Williams 1:41.686 0.995 23 laps
10 Valtteri Bottas Williams 1:41.830 1.139 22 laps
11 Fernando Alonso Ferrari 1:41.923 1.232 14 laps
12 Daniel Ricciardo Red Bull Racing 1:42.117 1.426 20 laps
13 Adrian Sutil Sauber-Ferrari 1:42.365 1.674 21 laps
14 Daniil Kvyat STR-Renault 1:42.869 2.178 21 laps
15 Esteban Gutierrez Sauber 1:42.904 2.213 23 laps
16 Jules Bianchi Marussia-Ferrari 1:43.825 3.134 18 laps
17 Marcus Ericsson Caterham 1:45.775 5.084 24 laps
18 Max Chilton Marussia-Ferrari 1:46.911 6.220 10 laps
19 Kamui Kobayashi Caterham 1:51.180 10.489 5 laps
20 Sergio Perez Force India No time 2 laps
21 Pastor Maldonado Lotus No time 2 laps
22 Romain Grosjean Lotus No time 4 laps