Updated

Lewis Hamilton secured his fourth consecutive pole position with a perfectly-timed lap in rollercoaster weather conditions in the final seconds of Saturday's qualifying session for Sunday's Belgian Grand Prix.

The 28-year-old Briton, in his Mercedes, grabbed his fifth pole of the year and 31st of his career with a late lap that saw him clock a best lap in two minutes and 1.012 seconds.

This came just a second after Australian Mark Webber and his Red Bull team-mate defending world champion German Sebastian Vettel had gone successively fastest with laps of 2:01.325 and 2:01.200.

Hamilton's lap delivered a final stunning moment of drama at the very end of a qualifying hour packed with incident and shocks as sweeping rain produced rapidly-changing conditions.

Vettel, the series leader, wound up second ahead of Webber with Hamilton's Mercedes team-mate German Nico Rosberg fourth ahead of Briton Paul Di Resta of Force India and Briton Jenson Button sixth for McLaren.

It brought Hamilton his seventh front row start of the season on a memorable afternoon from start to finish.

In quintessentially capricious Spa conditions, with the track drying out following a pre-session downpour, the first part of qualifying saw the Caterham and Marussia teams create a surprise after making an early switch from 'wet' tyres to intermediates.

This resulted in a dramatic final few minutes to Q1 that saw Alonso fastest ahead of a rejuvenated Hamilton with, remarkably, Dutchman Guido van der Garde taking third for Caterham ahead of Rosberg.

Marussia also delivered a shock with Frenchman Jules Bianchi 11th and Briton Max Chilton 16th, his first experience of progressing.

Out went Williams duo Venezuelan Pastor Maldonado and Finn Valtteri Bottas in 17th and 20th places along with luckless Frenchman Jean-Eric Vergne, who had been fast in dry conditions, and his Toro Rosso team-mate Australian Daniel Ricciardo - the man tipped to be switching to Red Bull alongside Vettel next year.

The circuit continued to dry in Q2 and the drivers responded by switching to softer compound tyres as the top contenders, including Hamilton, Rosberg and Vettel, left their running until the final five minutes.

As the lap times tumbled, this produced a frantic finish that saw Raikkonen quickest in 1:48.296 and Hamilton scraping through to the top ten shootout in 10th place.

The men who missed the cut were German Nico Hulkenberg of Sauber, German Adrian Sutil of Force India, Mexican Sergio Perez in the second McLaren, Dutchman Giedo van der Garde of Caterham - in a personal best qualifying slot of 14th - and the Marussia pairing, albeit in rarefied air mid-grid.

Just as Q3 began, rain fell again, a wave of raised umbrellas sweeping around distant 'Malmedy' and 'Stavelot' sections of the circuit. Adventurously, the whole field rushed out on slick tyres in pursuit of an early fast lap, except for one.

Just as quickly, the field lapped and returned to the pits for intermediate tyres leaving only Di Resta - who had delayed his start - on track, with the best choice of tyres, to clock 2:02.332.

Ferrari were swift in sending out Massa as the rain fell and he clocked a lap that saw him 1.727 seconds slower than the Scot as the remainder of the field risked running hard in heavy rain in the final minutes before it eased for a furious finale as the chequered flag fell.