It was too close for comfort in Singapore for Red Bull who decided to save an unused set of option tires for the race. Nico Rosberg came very, very close to nipping the top spot from Vettel.
I went to the onboard and lined up the two runs, which were just 0.091 of a second apart and it's quite interesting to see the different characteristics between the cars and the two drivers side by side.
I encourage you to stop the clip in various places and compare. You will find Vettel almost always is braking later and carries less speed into the apex than Rosberg but is consistently faster from mid corner on.
The Mercedes is quite a bit quicker in a straight line 298 km/h vs 292 for the Red Bull, but Vettel knows how to take advantage of the extra downforce the RB9 is producing and, on those short straights, his advantage in speed will pay off if he's ahead. Were he to be behind after the first corner, the deficit in top speed will make it hard for him to pass.
Check the video after the break.
Singapore GP Qualifying results
Pos Driver Team/Car Time Gap 1. Sebastian Vettel Red Bull-Renault 1m42.841s 2. Nico Rosberg Mercedes 1m42.932s +0.091s 3. Romain Grosjean Lotus-Renault 1m43.058s +0.217s 4. Mark Webber Red Bull-Renault 1m43.152s +0.311s 5. Lewis Hamilton Mercedes 1m43.254s +0.413s 6. Felipe Massa Ferrari 1m43.890s +1.049s 7. Fernando Alonso Ferrari 1m43.938s +1.097s 8. Jenson Button McLaren-Mercedes 1m44.282s +1.441s 9. Daniel Ricciardo Toro Rosso-Ferrari 1m44.439s +1.598s 10. Esteban Gutierrez Sauber-Ferrari No time set Q2 cut-off time: 1m44.555s Gap ** 11. Nico Hulkenberg Sauber-Ferrari 1m44.555s +1.650s 12. Jean-Eric Vergne Toro Rosso-Ferrari 1m44.588s +1.683s 13. Kimi Raikkonen Lotus-Renault 1m44.658s +1.753s 14. Sergio Perez McLaren-Mercedes 1m44.752s +1.847s 15. Adrian Sutil Force India-Mercedes 1m45.185s +2.280s 16. Valtteri Bottas Williams-Renault 1m45.388s +2.483s Q1 cut-off time: 1m45.982s Gap * 17. Paul di Resta Force India-Mercedes 1m46.121s +1.925s 18. Pastor Maldonado Williams-Renault 1m46.619s +2.423s 19. Charles Pic Caterham-Renault 1m48.111s +3.915s 20. Giedo van der Garde Caterham-Renault 1m48.320s +4.124s 21. Jules Bianchi Marussia-Cosworth 1m48.830s +4.634s 22. Max Chilton Marussia-Cosworth 1m48.930s +4.734s 107% time: 1m51.489s * Gap to quickest in Q1 ** Gap to quickest in Q2