Mercedes were beaten by the Ferrari duo in the final practice session, ahead of qualifying at Bahrain International Circuit.
Vettel produced a fastest lap of 1:31.683 to finish 0.040 seconds clear of teammate Kimi Raikkonen at the head of the timesheets. Friday practice pace-setter Nico Rosberg in third 0.421secs adrift.
World champion Lewis Hamilton, who has been out-paced by Rosberg this weekend so far, was 0.056s further back.
Valtteri Bottas finished fifth for Williams, despite they are not trailing new ultra-short nose, while Haas enjoyed a strong session as Romain Grosjean finished sixth with teammate Esteban Gutierrez in eighth, split by Red Bull’s Daniil Kvyat.
The second Williams ace Felipe Massa followed in ninth ahead of Daniel Ricciardo who rounded out the top 10 in the sister Red Bull car.
Both Toro Rosso and Force India opted not to set times on supersoft tyres and Force India ended up 2.5 seconds off the pace, with Nico Hulkenberg and Sergio Perez finishing 18th and 19th respectively, Max Verstappen and Carlos Sainz made 15th and 16th in that order.
F1 debut speedy, Stoffel Vandoorne managed within four hundredths of a second of teammate Jenson Button, Vandoorne missing three quarters of the session due to an oil spillage. The McLaren duo were classified in 14th and 13th places respectively.