Alonso fastest at Monaco

The Spaniard's mark of a minute 15.123 seconds held for the final 38 minutes and was 0.105s quicker than the Briton's best.

Mercedes' Nico Rosberg was again third with Jenson Button fourth ahead of world champion Sebastian Vettel, fastest in the morning.

The session started with a flurry of P1s as the track filled up while Mark Webber, ultimately eighth behind Felipe Massa and Michael Schumacher, had put his gearbox issues behind him.

"It was an electrical issue, which meant he couldn't select gears - but it's all been changed and should be all right for this session," said Red Bull principal Christian Horner a few minutes in.

Webber, the only driver not to set a time in the first session, suffered issues with his KERS however.

Alonso was keen for Ferrari to lead the fight against the dominant Red Bulls and McLarens and seems to have his wish, converting his promising second spot in the first session into P1 in this one.

The double world champion produced some fast work in race mode too, lapping in the 1:18s on hard tyres with plenty of fuel on board compared to 1:19s for some of his rivals.

His first leading time was set 15 minutes in and lasted for half an hour, Vettel taking it over on fresh super-soft rubber.

Massa almost crashed the Ferrari twice in quick succession, just recovering it at the exit to Swimming Pool and on the final corner, and Vettel could not improve his benchmark on two further hot laps before returning to the pits.

Alonso then took half a second off it - his final time - while Rosberg jumped into second.

Schumacher leapt from 21st to seventh before Hamilton gained several places to go fourth then second with his best time.

Many of the drivers spent this final 30 minutes or so on longer runs. Heikki Kovalainen went up the Ste. Devote run-off for a third time this weekend late on before Vitaly Petrov smashed the front wing off his Renault and suffered rear suspension damage.

The only driver not to set a time was Tonio Liuzzi in the HRT.