Sebastian Vettel beat Jenson Button to the fastest time in a late battle for the top spot in the final practice session ahead of Indian Grand Prix qualifying.
Just under four tenths of a second separated the Red Bull and McLaren at the end of the hour, with their respective teammates Mark Webber and Lewis Hamilton third and fourth, ahead of the Ferraris.
The Red Bulls had been in command for the majority of the session, with Webber the first of the big guns to set a quick time, before Vettel hit the front and went ever faster until establishing a 1m26.311s benchmark.
When the late qualifying simulations began, Friday pacesetter Felipe Massa (Ferrari) was first to beat Vettel with a 1m26.058s, although his advantage lasted only moments before Button came through with a 1m25.942s.
The McLaren was deposed by Fernando Alonso's Ferrari, which lapped in 1m25.784s, but Button responded on his second flying lap of the run by jumping 0.6sec clear with a 1m25.191s. That looked like it might be sufficient to keep the Briton on top, as although Hamilton and Webber closed in, they were a few fractions of a second shy of Button's time. But the World Champion was still out and as the checkered flag fell, he produced a 1m24.824s to beat Button by 0.367sec and set himself up as pole favorite once again.
Behind Webber, Hamilton and Alonso, sixth-placed Massa's front wing continued to vibrate distinctively for much of the session, before apparently being replaced with a different specification for the final run, when it was more stable.
Force India looks strong heading into qualifying, with Paul di Resta seventh and Adrian Sutil ninth, split by Nico Rosberg's Mercedes. Both Mercedes had been in the top five until the soft tire runs. Michael Schumacher ended up 11th behind Sebastien Buemi's Toro Rosso.
Local favorite Narain Karthikeyan had a quick spin at the final corner early on but managed to head all the other new teams' drivers for quite a while in his HRT, before ending the morning 22nd.
The only other significant incident was a spin for Bruno Senna on the Lotus Renault driver's last lap, in which he was fortunate to miss the barriers, while plenty of drivers continued to explore the limits of the dusty track with minor errors.
Pos Driver Team/Car Time Gap Laps
1. Sebastian Vettel Red Bull-Renault 1m24.824s 18
2. Jenson Button McLaren-Mercedes 1m25.191s + 0.367s 15
3. Mark Webber Red Bull-Renault 1m25.203s + 0.379s 19
4. Lewis Hamilton McLaren-Mercedes 1m25.288s + 0.464s 16
5. Fernando Alonso Ferrari 1m25.784s + 0.960s 17
6. Felipe Massa Ferrari 1m26.058s + 1.234s 16
7. Paul di Resta Force India-Mercedes 1m26.785s + 1.961s 19
8. Nico Rosberg Mercedes 1m26.873s + 2.049s 22
9. Adrian Sutil Force India-Mercedes 1m26.958s + 2.134s 19
10. Sebastien Buemi Toro Rosso-Ferrari 1m27.146s + 2.322s 20
11. Michael Schumacher Mercedes 1m27.217s + 2.393s 21
12. Bruno Senna Renault 1m27.235s + 2.411s 20
13. Kamui Kobayashi Sauber-Ferrari 1m27.262s + 2.438s 19
14. Vitaly Petrov Renault 1m27.280s + 2.456s 18
15. Jaime Alguersuari Toro Rosso-Ferrari 1m27.387s + 2.563s 20
16. Sergio Perez Sauber-Ferrari 1m27.749s + 2.925s 21
17. Pastor Maldonado Williams-Cosworth 1m27.793s + 2.969s 17
18. Rubens Barrichello Williams-Cosworth 1m27.875s + 3.051s 20
19. Jarno Trulli Lotus-Renault 1m29.355s + 4.531s 21
20. Heikki Kovalainen Lotus-Renault 1m29.750s + 4.926s 19
21. Timo Glock Virgin-Cosworth 1m30.683s + 5.859s 23
22. Narain Karthikeyan HRT-Cosworth 1m30.900s + 6.076s 25
23. Jerome D'Ambrosio Virgin-Cosworth 1m32.851s + 8.027s 19
24. Daniel Ricciardo HRT-Cosworth 1m33.246s + 8.422s 16
All timing unofficial