Fernando Alonso claimed the final bragging rights before heading into qualifying for the Bahrain Grand Prix, but the presence of both Red Bulls next up on the timesheets suggests that the Spaniard is far from a cert for pole.
Alonso's time of 1min 33.247secs, set despite a spin earlier in the session, was the fastest of the weekend so far, but the Ferrari could not separate itself from the chasing pack, as no fewer than seven other drivers lapped within half a second. Vettel came closest to toppling Alonso from top spot, ending the 60-minute session just a tenth off the pace, but without having been able to complete his run on the softer Pirelli tyre before hitting traffic.
Team-mate Mark Webber was next up, a matter of hundredths further back, having held second spot for some time, while Kimi Raikkonen, Lewis Hamilton, Romain Grosjean and, most surprisingly of all, both Force India drivers all got to within 0.5secs off Alonso.
Hamilton's session ended, however, with the Mercedes driver limping back to the pits, having suffered a serious blow-out that not only trashed his tyre, but also took part of the suspension with it. Initial inspections suggest wishbone damage, which should only be time-consuming for the Brackley team. Prior to the incident, Hamilton had been able to out-pace team-mate Nico Rosberg, who ended the session in ninth spot, one place ahead of near namesake Nico Hulkenberg.
The Sauber driver, in turn, wound up ahead of the second Ferrari of Felipe Massa, the Brazilian unable to find his usual Sakhir pace to match Alonso, and Jenson Button, who was the faster of the two McLarens by a tenth, but also the first driver unable to break into the 1min 33s bracket. Massa, like Raikkonen, put in a lot of laps during the session.
A little further back, Valtteri Bottas again gave Williams a boost by splitting the two Toro Rossos, but Pastor Maldonado was only saved from being the slowest of the recognised midfield runners by Sauber's decision to prepare Esteban Gutierrez for Sunday's race rather than the more immediate problem of qualifying. The Mexican rookie faces a five-place grid penalty for his assault on Adrian Sutil in Shanghai and could theoretically find himself on the back row come Sunday afternoon.
Charles Pic again had the upper hand in the battle between Caterham and Marussia, although the Frenchman again raised eyebrows by closing the door on Vettel as the world champion shaped to pass late in the session. Jules Bianchi was next up, while Giedo van der Garde was able to get the better of Max Chilton after the Briton was sidelined in the pits with just seven laps to his name.