Red Bull returned to the top in opening practice for the Malaysian Grand Prix, as Mark Webber led the way at Sepang on Friday morning.
His team-mate Sebastian Vettel was back in third, behind Melbourne winner Kimi Raikkonen's Lotus.
The Finn had not joined the track until 55 minutes into the session as his mechanics worked to replace a KERS battery.
But Raikkonen needed no time to get up to speed as he immediately put a 1m37.003s lap, 0.068 seconds down on pacesetter Webber and sufficient to split the Red Bulls.
Although Raikkonen was late out of the garage, he did not miss out on much running as it took 34 minutes for anyone to set a flying lap.
Most of the pack waited in the pits for circuit conditions to improve, then set their fastest times in a 10 minute spell of short runs before switching to heavy fuel for the rest of the morning.
Those long runs featured significant pace drop-off as tyres wore, with Lewis Hamilton in particular complaining of his Pirellis being "destroyed".
Behind Webber, Raikkonen and Vettel, Fernando Alonso put the leading Ferrari fourth, followed by Nico Rosberg's Mercedes.
Adrian Sutil followed up his star turn in Melbourne with sixth place, despite having to pit for repairs after damaging his Force India's wing on a kerb.
Alonso and Sutil's respective team-mates Felipe Massa and Paul di Resta were seventh and eighth, with Hamilton and Romain Grosjean completing the top 10.
Elsewhere, form appeared similar to Australia, as McLaren, Williams and Sauber were all outside the top 10. Sauber driver Esteban Gutierrez committed the only significant error of the session as he went off at Turn 14.
Pos Driver Team/Car Time Gap Laps
1. Mark Webber Red Bull-Renault 1m36.935s 15
2. Kimi Raikkonen Lotus-Renault 1m37.003s + 0.068s 15
3. Sebastian Vettel Red Bull-Renault 1m37.104s + 0.169s 21
4. Fernando Alonso Ferrari 1m37.319s + 0.384s 13
5. Nico Rosberg Mercedes 1m37.588s + 0.653s 19
6. Adrian Sutil Force India-Mercedes 1m37.769s + 0.834s 17
7. Felipe Massa Ferrari 1m37.771s + 0.836s 15
8. Paul di Resta Force India-Mercedes 1m37.773s + 0.838s 15
9. Lewis Hamilton Mercedes 1m37.840s + 0.905s 18
10. Romain Grosjean Lotus-Renault 1m37.915s + 0.980s 17
11. Jenson Button McLaren-Mercedes 1m38.173s + 1.238s 16
12. Pastor Maldonado Williams-Renault 1m38.673s + 1.738s 16
13. Sergio Perez McLaren-Mercedes 1m38.830s + 1.895s 17
14. Nico Hulkenberg Sauber-Ferrari 1m39.054s + 2.119s 17
15. Esteban Gutierrez Sauber-Ferrari 1m39.204s + 2.269s 16
16. Valtteri Bottas Williams-Renault 1m39.208s + 2.273s 19
17. Jean-Eric Vergne Toro Rosso-Ferrari 1m39.284s + 2.349s 17
18. Daniel Ricciardo Toro Rosso-Ferrari 1m39.567s + 2.632s 16
19. Giedo van der Garde Caterham-Renault 1m40.728s + 3.793s 17
20. Jules Bianchi Marussia-Cosworth 1m40.996s + 4.061s 14
21. Charles Pic Caterham-Renault 1m41.163s + 4.228s 18
22. Max Chilton Marussia-Cosworth 1m41.513s + 4.578s 14