Just under four tenths of a second separated the Red Bull and McLaren at the end of the hour, with their respective team-mates 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 - though 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 0.6s 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 world champion Vettel was still out and as the chequered flag fell, he produced a 1m24.824s to beat Button by 0.367 seconds and set himself up as pole favourite 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 NicoRosberg's Mercedes. Both Mercedes had been in the top five until the soft tyre runs. Michael Schumacher ended up 11th behind SebastienBuemi's Toro Rosso.
Local favourite 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 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.
1m25.191s + 0.367s
1m25.203s + 0.379s
1m25.288s + 0.464s
1m25.784s + 0.960s
1m26.058s + 1.234s
Paul di Resta
1m26.785s + 1.961s
1m26.873s + 2.049s
1m26.958s + 2.134s
1m27.146s + 2.322s
1m27.217s + 2.393s
1m27.262s + 2.438s
1m27.280s + 2.456s
1m27.387s + 2.563s
1m27.749s + 2.925s
1m27.793s + 2.969s
1m27.875s + 3.051s
1m29.355s + 4.531s
1m29.750s + 4.926s
1m30.683s + 5.859s
1m30.900s + 6.076s
1m32.851s + 8.027s
1m33.246s + 8.422s
Issue: 192 | Autocar India: August 2015
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