Ferrari team-mate Kimi Raikkonen had set the pace with just over half of the one-hour session completed having been among a group of drivers to set times on ultra-soft Pirellis early on, which included Daniel Ricciardo and Vettel.
With just over forty minutes to go, Nico Rosberg, who had been fifth fastest behind Mercedes team-mate Lewis Hamilton with both using the slower super-soft Pirellis early on, went fastest after bolting on the fastest tyre.

[Free Practice 3: Full result]

Abu Dhabi Grand Prix
Rosberg: Abu Dhabi was my toughest race
28/11/2016 AT 10:29
Seconds after Rosberg knocked Raikkonen off top spot, Hamilton posted a time 0.103s quicker to take top spot.
But Vettel, on a fresh set of ultra-softs, then went 0.137s faster than Hamilton with 11 minutes remaining to secure top spot.
Red Bull driver Max Verstappen and Raikkonen slotted in second and third on their late runs on ultra-softs, which left Hamilton and Rosberg, who remain favourite to qualify on the front row, down in fourth and fifth after completing their qualifying simulation runs before everyone else.
Ricciardo ended the session a distant sixth, a second off the pace, after failing to exploit the potential of his ultra-soft tyres.
Force India driver Sergio Perez was seventh fastest, less than a tenth off Ricciardo, while team-mate Nico Hulkenberg ended up eighth after missing half of the session with a fuel system problem.
Williams driver Valtteri Bottas and Haas's Esteban Gutierrez, who took a fresh Ferrari engine ahead of this session, rounded out the top 10, ahead of McLaren driver Fernando Alonso.
Renault's Jolyon Palmer was 12th fastest ahead of Jenson Button, while Felipe Massa didn't get the best out of his final set of tyres after a spin at Turn 6 right at the start of his run.
Toro Rosso returned to the track after stopping running in yesterday's session amid concerns it and the FIA had about safety following two punctures believed to be car-related.
Carlos Sainz Jr and Daniil Kvyat completed only 23 laps between them, with Sainz best placed in 18th place.
Abu Dhabi Grand Prix
Abu Dhabi was my toughest race - Rosberg
28/11/2016 AT 10:04
Abu Dhabi Grand Prix
Hamilton claims pole for make-or-break season finale
26/11/2016 AT 14:05