Vettel snatches top spot

Webber completed only three laps, none of them timed, before a gearbox failure put paid to his session. The team's mechanics will work quickly to try and repair the RB7 for the afternoon session as the Australian seeks to regain lost ground on German Vettel.

Fernando Alonso of Ferrari was second behind world champion Vettel, whose time of a minute 16.619 seconds set with the chequered flag out was 0.113s faster than the Spaniard.

Nico Rosberg was third for Mercedes ahead of Felipe Massa (Ferrari), with the McLarens of Britons Lewis Hamilton and Jenson Button fifth and sixth.

Halfway through the 90-minute session Webber retired to the garage after becoming stuck in gear. Up to that point Narain Karthikeyan, Pastor Maldonado and Sergio Perez had had time in P1 as the big guns held back.

There was time for Felipe Massa to set the leading time and improve upon it once before the drama of a stopped session, due to water bubbling up to the track surface on the start-finish straight from a leaking underground pipe. Vettel had just gone P3.

When it restarted around six minutes later, Hamilton, Rosberg and Alonso battled it out at the top before Vettel began to make his move. With Hamilton in the pits, he moved up the order - he had dropped a way back down - in stages, eventually usurping Massa at the summit with 13 minutes remaining.

Adrian Sutil improved in tandem with the German - until his final, pacesetting laps - but ultimately finished in eighth, behind Maldonado.

With eight minutes remaining Michael Schumacher lost his Mercedes entering Ste. Devote and damaged the front, but was not travelling quickly and emerged unscathed.

With the minutes ticking away, Rosberg leapt into P1 then Vettel again set the benchmark with 1:16.781.

Twice world champion Alonso, desperate for Ferrari to give him a car capable of competing with Red Bull and McLaren, wrung enough from the 150 Italia to grab P1 only for Vettel to snatch the headlines despite having to back off on the previous lap.