Nico Rosberg was denied a clean sweep of the practice sessions ahead of the Bahrain Grand Prix as Ferrari got the better of Mercedes in P3 at Sakhir.
Ferrari endured problems in Friday's second session, with Kimi Raikkonen and Sebastian Vettel well off the pace and the latter undermined by an issue that brought his car to a halt with 15 minutes remaining.
However, it was Vettel who set the fastest time on Saturday, stopping the clock at one minute and 31.683 seconds to pip team-mate Raikkonen by 0.040 seconds.
Rosberg and Hamilton were almost half a second adrift in third and fourth respectively, with Williams' Valtteri Bottas (+0.992secs) rounding out the top five and Haas drivers Romain Grosjean (+1.399secs) and Esteban Gutierrez (+1.654secs) taking sixth and eighth.
Mercedes, who claimed victory in the season-opening Australian Grand Prix through Rosberg a fortnight ago, remain favourites to claim pole position in the day's subsequent qualifying, but Ferrari could take heart from their pace ahead of that shootout.
1. Sebastian Vettel (Ferrari) 1:31.683
2. Kimi Raikkonen (Ferrari) 1:31.723
3. Nico Rosberg (Mercedes) 1:32.104
4. Lewis Hamilton (Mercedes) 1:32.160
5. Valtteri Bottas (Williams) 1:32.675
6. Romain Grosjean (Haas) 1:33.082
7. Daniil Kvyat (Red Bull) 1:33.113
8. Esteban Gutierrez (Haas) 1:33.337
9. Felipe Massa (Williams) 1:33.363
10. Daniel Ricciardo (Red Bull) 1:33.519