Sebastian Vettel beat Red Bull team-mate Mark Webber to the fastest time in Friday's second Singapore Grand Prix practice session after a mighty battle between the duo.
Championship leader Vettel and Webber swapped the top spot repeatedly on the soft-compound tyres early on. Webber won that battle, with a time of 1m46.157s giving him a 0.251-second advantage over the German, who had just usurped his original mark.
Vettel blew that pace away when he moved onto supersofts and lapped in 1m44.249s.
Webber's response was compromised by a firm clout of the wall near the end of the lap, leaving him 0.604s down in the end.
Third-placed Nico Rosberg, who pipped Mercedes team-mate Lewis Hamilton by 0.110s, was a second off Vettel's pace.
Steering and brake issues again limited Romain Grosjean's mileage, but did not stop him putting his Lotus fifth - just 0.043s behind Hamilton - during what little running he managed.
That placed him ahead of Fernando Alonso and Jenson Button in the top Ferrari and McLaren respectively, and Kimi Raikkonen in the second Lotus.
Adrian Sutil and Sergio Perez completed the top 10.
Bar minor brushes such as Webber's, everyone managed to stay away from the barriers with the exception of Pastor Maldonado, whose Williams required a new front wing.
Pos Driver Team Time Gap Laps 1. Sebastian Vettel Red Bull-Renault 1m44.249s 34 2. Mark Webber Red Bull-Renault 1m44.853s +0.604s 30 3. Nico Rosberg Mercedes 1m45.258s +1.009s 34 4. Lewis Hamilton Mercedes 1m45.368s +1.119s 33 5. Romain Grosjean Lotus-Renault 1m45.411s +1.162s 18 6. Fernando Alonso Ferrari 1m45.691s +1.442s 32 7. Jenson Button McLaren-Mercedes 1m45.754s +1.505s 30 8. Kimi Raikkonen Lotus-Renault 1m45.778s +1.529s 32 9. Adrian Sutil Force India-Mercedes 1m46.002s +1.753s 27 10. Sergio Perez McLaren-Mercedes 1m46.025s +1.776s 31 11. Daniel Ricciardo Toro Rosso-Ferrari 1m46.406s +2.157s 34 12. Jean-Eric Vergne Toro Rosso-Ferrari 1m46.429s +2.180s 33 13. Paul di Resta Force India-Mercedes 1m46.606s +2.357s 33 14. Nico Hulkenberg Sauber-Ferrari 1m46.808s +2.559s 36 15. Felipe Massa Ferrari 1m46.870s +2.621s 33 16. Esteban Gutierrez Sauber-Ferrari 1m47.287s +3.038s 29 17. Valtteri Bottas Williams-Renault 1m47.434s +3.185s 33 18. Pastor Maldonado Williams-Renault 1m47.761s +3.512s 25 19. Giedo van der Garde Caterham-Renault 1m49.434s +5.185s 34 20. Charles Pic Caterham-Renault 1m49.526s +5.277s 34 21. Max Chilton Marussia-Cosworth 1m49.619s +5.370s 33 22. Jules Bianchi Marussia-Cosworth 1m49.731s +5.482s 30