Highlights - Belgian GP qualifying
Belgian Grand Prix, 27-29 August, Spa
Coverage: Live on BBC One, Red Button, BBC Sport website and Radio 5 live
Full details of practice, qualifying and Sunday's race
Championship leader Mark Webber will start Sunday's Belgian Grand Prix from pole position after a rain-affected qualifying session in Spa.
The Australian maintained Red Bull's stranglehold on qualifying with a lap of one minute 45.778 seconds for their 13th pole out of 14 races this season.
But McLaren's Lewis Hamilton produced a superb performance to take second, ahead of Renault's Robert Kubica.
Webber's team-mate Sebastian Vettel was only fourth fastest.
With Jenson Button's McLaren on the second row in fifth, it was a bad day for Ferrari, for whom Felipe Massa was sixth and Fernando Alonso a hugely disappointing 10th.
"It's certainly a nice venue to get pole position, but the conditions were difficult and we were all tested," said Webber.
"It was a good lap but you never know whether it's going to be enough, and Lewis did a pretty good lap to get second when La Source [turn one] was pretty greasy. But the race won't be won on the first lap tomorrow."
Top three drivers - Belgian GP qualifying
Hamilton, who clocked 1:45.863, said that without the rain that began to fall during his final flying lap, he might have been fast enough to take pole.
"There was a big cloud coming over just before the last run was starting and it was so tricky because the rest of the track was dry but there was one corner that was a bit damp," he said.
"When we came back out I asked if it was dry, and they said yes, and I went for it and hit the brakes and went straight on and lost three-and-a-half tenths there, so pole would have been possible.
"These conditions are the toughest for racing because you're constantly having to re-evaluate your grip levels, it's an art and you can get caught out so easily.
"But the good thing is the car is handling very well, and I'm excited about the race."
Pole position is less important at Spa than at many other circuits in the Formula 1 calendar - in the last 53 Grands Prix at the great Belgian track, only 13 have been won by the driver starting from the front.
But, given Red Bull's speed in qualifying this season, McLaren will take encouragement from splitting Webber and Vettel.
Kubica (1:46.100) was pleased to have fulfilled the promise Renault had been showing throughout practice in qualifying, with the team running a new 'F duct' aerodynamic device on their car for the first time this weekend.
"Third is maybe surprisingly good, but yesterday and this morning we were right there, so it's a good feeling," he said.
The Pole admitted to some relief he had hung on to third after a fuel pick-up problem had prevented him attempting a second flying lap in Q3.
"We had a bit of a bad moment when the car stopped running approaching the last chicane on the in-lap, and we knew we would not have time for a second attempt in Q3 so I was praying for rain.
"I think Red Bull is out of reach and McLaren is very fast, but we will try our best and see."
Alonso, meanwhile, attempted to shrug off his qualifying result. "I'm not too worried - the race is tomorrow, and in changing conditions anything can happen," said the Spaniard, who set the pace in Friday's practice.
Blue skies at the start of qualifying were a surprise given the rain that had been forecast.
But the track was still damp from the heavy showers that had fallen during final practice, which meant one way or another, grip levels were going to change markedly during the session.
Being on the track at the right time was also likely to be crucial, and all the drivers were out quickly to get in an early lap on slick tyres.
Hamilton enjoys challenging Spa conditions
Button went straight out on his softer tyres, but there was immediate frustration when Vitaly Petrov slid off on his warm-up lap at turn nine, causing the session to be temporarily red flagged while the stricken Renault was recovered.
When the session restarted all the cars hit the track on soft slicks in a desperate attempt to get in a banker lap, but rain began to fall almost immediately.
Parts of the circuit were wet when others were still dry and the result was chaos, with several cars going off at Stavelot, and Virgin's Lucas Di Grassi spinning in the centre of the track.
With six minutes of Q1 remaining, Vettel was in 18th, but a lap of 1:58.487 on intermediate tyres lifted him to safety. The big losers in Q1 were Sauber, both of whose drivers crashed out.
With the sun coming out and the track drying rapidly, slick tyres were back on for Q2. Both Ferraris briefly visited the gravel, and appeared to be struggling to make their tyres work.
Though Button was the first to get under 1:48, it was Hamilton who again topped the time sheets with 1:46.211.
Both Mercedes failed to make the top 10, and with Michael Schumacher facing a 10-place penalty for his driving in Hungary, the former world champion will start from 21st.
To complete another bad day for the former Brawn team, Schumacher's team-mate Nico Rosberg had to change his gearbox, incurring a five-place penalty.
Rain was again beginning to fall when the top 10 hit the track for their final flying lap.
Ferrari once more failed to find the necessary speed; Alonso, who had been the only front-runner not to go straight out on his option tyres, found himself badly compromised by the damp track at La Source.
Hamilton, with a superb effort despite losing several tenths of a second at La Source, dragged his McLaren ahead of Kubica on to the front row, but even Hamilton could not find enough time to catch Webber, whose first effort in Q3 secured pole.
Timo Glock was later given a five-place grid penalty for blocking Hispania's Sakon Yamamoto.
Glock had qualified in 15th, which equalled his best qualifying result for Virgin in Malaysia.
Toro Rosso's Sebastien Buemi also received a three-place penalty for impeding Rosberg.