- Lewis Hamilton claims his fourth successive pole position this season
- Mercedes driver denies championship leader Sebastian Vettel at Spa
- Vettel qualifies second ahead of Red Bull teammate Mark Webber
- Title contenders Kimi Raikkonen and Fernando Alonso off the pace
Lewis Hamilton couldn't believe his luck after snatching a fourth successive pole position at a rain-affected qualifying session for Sunday's Belgian Grand Prix.
The Mercedes driver, who won the last race in Hungary before Formula One's four-week mid-season break, gave himself a great chance of reducing Sebastian Vettel's championship lead after his last-minute heroics at Spa on Saturday.
Force India's Paul Di Resta had been poised for the first pole position of his career after making a bold tire gamble, but as the rain eased and the track dried his best time was beaten by Mark Webber.
Vettel looked to have edged out his Red Bull teammate as he set the quickest time of two minutes 1.2 seconds, only for Hamilton to charge through right at the end with 2:1.012.
"When I started that last lap I thought, 'Oh my God!' as I was seventh or eighth and about three seconds down," the 2008 world champion said after claiming the 31st pole of his career -- putting him seventh on the all-time list.
"I ran slightly wide at the first corner and I dropped to five, six seconds back, so I didn't know what was going on," Hamilton, who won at Spa in 2010, told reporters.
"But I kept pushing. It's a blessing I am up here. Generally I feel comfortable in changing conditions when I can find the limit.
"I pushed through the middle sector and really caned it. I feel so fortunate to get pole."
Vettel, who leads fourth-placed Hamilton by 48 points, expects similar entertainment during the race with mixed weather again forecast.
"We all went out on slicks -- which was entertaining when it started to rain heavily," the German said.
"Then it stopped raining and the circuit came back quickly, but I saw Lewis catching me up in the last lap, so I could have gone quicker.
"I was quite close to pole, but all in all it was a good day for the team. Let's now see what happens tomorrow when we expect similar conditions."
Di Resta had to settle for fifth -- behind Mercedes' Nico Rosberg but ahead of Hamilton's former McLaren teammate Jenson Button, who won the race last year.
Romain Grosjean qualified seventh ahead of Lotus teammate Kimi Raikkonen, second in the championship and a four-time winner at Spa.
Fernando Alonso, a point behind the Finn in the standings, was another place back in qualifying as the Spaniard took ninth ahead of Ferrari teammate Felipe Massa.
Meanwhile, Pirelli's investigation into punctures suffered by Vettel and Alonso during Friday's practice revealed that the cause was a piece of metal that had fallen off a car -- not the tires.
Drivers had been concerned after earlier problems with the rubber compounds at July's British Grand Prix and were worried there may be a repeat at the high-speed Belgian track.
"There are certainly no tire-related issues," Pirelli's motorsport director Paul Hembery said.
"We've seen no signs of fatigue. From our point of view there is no reason to be concerned."
Hembery did express concern at reports Michelin may return to F1 as a tire supplier, despite Pirelli having a deal in place with F1 boss Bernie Ecclestone.
For Michelin to be involved for the first time since 2006, governing body the FIA would have to announce a tender at next month's World Motor Sport Council in Croatia.
"We've contracts in place and we'd hope people would respect them," Hembery told the UK Press Association.
"Quite frankly, a tender in September, when we will be running in January, would be farcical.
"If you wanted to do that then it should have been done in September of last year. Everybody will look ridiculous in that scenario."
Meanwhile, in motorcycling's elite MotoGP competition, Cal Crutchlow set a new lap record at Brno as he claimed a surprise pole position for Sunday's Czech Grand Prix.
The British rider beat the quickest time set last year by world champion Jorge Lorenzo, and will head the grid for the second time this season for Monster Yamaha Tech 3.
Lorenzo qualified fifth for the Yamaha factory team, with seven-time world champion teammate Valentino Rossi seventh.
The Honda factory team's riders Marc Marquez and Dani Pedrosa were third and fourth, though they too were upstaged by an independent entry as Alvaro Bautista took second on the timesheets for Honda Gresini.