Lewis Hamilton has finished fastest in the second practice session ahead of this weekend's Malaysian Grand Prix.
The Mercedes driver, who claimed victory in the opening race of the season in Australia a fortnight ago, recorded a time of 1:39.790 to edge out Ferrari's Kimi Raikkonen.
Having suffered numerous problems in the first session of the day, the Englishman was equally frustrated for the opening 30 minutes of the second, before powering through to come out on top at the Sepang International Circuit.
Hamilton was not alone in having issues with his car, though, as a number of drivers reported poor grip levels throughout the race.
Mercedes teammate Nico Rosberg was one of those who suffered after failing to get a clean run on the fastest tyres, while McLaren duo Fernando Alonso and Jenson Button were way down in 16th and 17th place respectively.
Elsewhere, there was some encouragement for Red Bull, as Daniil Kvyat finished in fourth, ahead of Williams duo Valtteri Bottas and Felipe Massa.
Full standings:
1. Lewis Hamilton (Mercedes)
2. Kimi Raikkonen (Ferrari)
3. Nico Rosberg (Mercedes)
4. Daniil Kvyat (Red Bull)
5. Valtteri Bottas (Williams)
6. Felipe Massa (Williams)
7. Sebastian Vettel (Ferrari)
8. Max Verstappen (Toro Rosso)
9. Marcus Ericsson (Sauber)
10. Daniel Ricciardo (Red Bull)
11. Pastor Maldonado (Lotus)
12. Felipe Nasr (Sauber)
13. Sergio Perez (Force India)
14. Carlos Sainz (Toro Rosso)
15. Nico Hulkenberg (Force India)
16. Fernando Alonso (McLaren)
17. Jenson Button (McLaren)
18. Romain Grosjean (Lotus)
19. Will Stevens (Manor Marussia)
20. Roberto Merhi (Manor Marussia)
