Webber on Spa pole

Webber's Red Bull team-mate Sebastian Vettel, third in the title fight, will start on the front row - but Renault's Robert Kubica pipped him to third place on the grid.

Jenson Button, team-mate of Hamilton at McLaren, was fifth ahead of Felipe Massa who went wide on his final quick lap in the Ferrari.

In the leading Scuderia F10 Fernando Alonso, who topped both practice sessions on Friday, came out worst in the top-10 shootout with Williams duo Rubens Barrichello and Nico Hulkenberg seventh and ninth.

They sandwiched Force India's Adrian Sutil, who took a shock pole at Spa last season.

The session began in spectacular fashion, with Vitaly Petrov's second-minute crash beginning what turned out to be a bittersweet day for Renault.

By the time the session restarted rain was imminent, and the entire field of cars - minus the Russian - raced out to set a quick lap-time.

Three minutes later there was a six-car spin at Stavelot with plenty of cars racing through the turn at full tilt under yellow flag conditions and dodging those seeking to rejoin.

There was no collision, but the incident is being investigated by stewards.

The rain had begun before the first restarted laps were over with but eased off soon after, leaving most drivers on intermediate tyres but minutes later reverting back to slicks.

Renault's nightmare scenario was averted when Kubica climbed out of the bottom-seven drop zone late on, taking top spot.

But Sauber's was only just beginning: first Kamui Kobayashi crashed into the barriers then team-mate Pedro de la Rosa followed suit elsewhere on the circuit.

In Q2 Alonso had a scare when he just managed to keep rolling through the deep gravel to rejoin - which may have contributed to his struggles in Q3 - while there was disappointment for Mercedes as both Michael Schumacher and German compatriot Nico Rosberg just failed to reach the final mini-session.

Seven-times champion Schumacher, who describes the circuit as his "living room", will start 21st as he serves a penalty for the incident with Barrichello in Hungary. Rosberg has a five-place penalty himself.

In Q3 Hamilton was fifth as the championship contenders emerged for one final push, and with rain falling in the pitlane.

He did enough with his final lap to go second behind Webber, while Button jumped to fifth with his last effort.