Despite using the same engine that put him out of the Australian GP, Lewis Hamilton topped the opening practice session at Sepang ahead of Kimi Raikkonen.
Hamilton retired from the season-opening Australian GP with an engine issue but it proved to be a quick fix for Mercedes and the Brit was back in his W05 with the exact same engine at Sepang.
Putting in the laps, 19 in total, the Mercedes driver clocked a 1:40.691 to beat Raikkonen by 0.152.
It was a much improved session for the Ferrari driver, who revealed he was happier with his F14T's balance on Friday morning.
Nico Rosberg was third for Mercedes, finishing ahead of the McLarens of Jenson Button and Kevin Magnussen.
The latter had a minor issue that led to him switching off his engine, however, with the marshals help he was pushed back into the pits and was soon back in the action.
Jean-Eric Vergne continued Toro Rosso's early season form, finishing sixth quickest, 0.711s down, while Sebastian Vettel was a further 0.121s down.
Nico Hulkenberg and Felipe Massa were the final two drivers to get within a second of Hamilton's P1 time while Valtteri Bottas completed the top ten.
There were more issues at Lotus, who covered just six laps between both drivers.
Romain Grosjean stopped out on track with a battery issue but did make it back out in the final five minutes while Pastor Maldonado, after a lengthy period in the pits following his installation lap, pulled his E22 into the pits with smoke coming out the back of the car.
Meanwhile, Sergio Perez also managed just two laps in his Force India while Kamui Kobayashi covered five before Caterham "found a problem with his energy store so it's floor off to change it so he can run again in FP2."
01 Lewis Hamilton Mercedes 1:40.691 19 laps
02 Kimi Raikkonen Ferrari 1:40.843 +0.152 20 laps
03 Nico Rosberg Mercedes 1:41.028 +0.337 19 laps
04 Jenson Button McLaren 1:41.111 +0.420 20 laps
05 Kevin Magnussen McLaren 1:41.274 +0.583 18 laps
06 Jean-Eric Vergne Toro Rosso 1:41.402 +0.711 15 laps
07 Sebastian Vettel Red Bull 1:41.523 +0.832 9 laps
08 Nico Hulkenberg Force India 1:41.642 +0.951 19 laps
09 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 1:42.117 +1.426 20 laps
13 Adrian Sutil Sauber 1:42.365 +1.674 21 laps
14 Daniil Kvyat Toro Rosso 1:42.869 +2.178 21 laps
15 Esteban Gutierrez Sauber 1:42.904 +2.213 23 laps
16 Jules Bianchi Marussia 1:43.825 +3.134 18 laps
17 Marcus Ericsson Caterham 1:45.775 +5.084 24 laps
18 Max Chilton Marussia 1:46.911 +6.220 10 laps
19 Kamui Kobayashi Caterham 1:51.180 +10.489 5 laps
20 Romain Grosjean Lotus No time 4 laps
21 Sergio Perez Force India No time 2 laps
22 Pastor Maldonado Lotus No time 2 laps