If there's any job which is more difficult than being an F1 driver, then it must be as a meteorologist at Spa-Francorchamps. The weather was all over the place and dominated qualifying for the Belgian Grand Prix on Saturday afternoon, causing upsets at the end of Q1 and then teasing us with the possibility of a maiden pole position for Force India's Paul di Resta, only for the weather to bait-and-switch at the last second and instead hand glory to Lewis Hamilton who claimed the top spot for the fourth race in a row.

Hamilton will start Sunday's race alongside Sebastian Vettel, with Mark Webber alongside Nico Rosberg on the second row and di Resta pushed back in the final seconds of Q3 to join Jenson Button on row three. But those bald end positions only tell a small part of the story of Saturday afternoon's action in Belgium.

It had been clear that qualifying was imminent when the heavens opened and heavy rain began to fall just ten minutes before the green light for Q1. That made things interesting for the drivers, who had enjoyed a dry FP3 session earlier in the day and who now had to get their heads around an altogether different situation for qualifying at the 20-turn, 4.352-mile Circuit de Spa-Francorchamps. At the very least, it banished any concerns about tyre safety, as the teams made haste to bolt on wet weather tyres.

Fearing that track conditions would only deteriorate, all 22 drivers were quickly out on track to set a lap, with Williams' Pastor Maldonado the first to slip off the track at Les Combes as the Mercedes drivers set the early pace with Nico Rosberg's 2:06.865s putting him over a tenth ahead of team mate Lewis Hamilton and Red Bull's Mark Webber.

The wet tyres quickly did their job clearing a dry line around the circuit as the rain stated to ease off again, meaning that new faces leapt to the top every few seconds. Sebastian Vettel leapt up from tenth spot on his first run to the top spot next time around with a time of 2:06.279s, and teams were soon on the radio to caution their drivers to take care of the intermediates and not allow them to overheat too quickly while the strategies tried to determine the tipping point for a change to the slick compounds.

Jut after the midway point of the 20 second Q1 session Lewis Hamilton reclaimed the top spot for Mercedes with a lap of 2:04.618s over a second faster than Lotus F1's Kimi Raikkonen and Ferrari's Fernando Alonso. Rosberg quickly pushed the benchmark time down to 2:03.883s which also had the effect of bumping Max Chilton out of the 107 per cent zone at the bottom of the timing screens. Marussia decided to throw caution to the wind and switch Chilton and his team mate Jules Bianchi to a set of mediums tyres, with Caterham doing likewise for Giedo van der Garde and Charles Pic. The gamble didn't pay off, van der Garde struggling through Les Combes while Chilton kept it on the island but failed to find the expected boost in pace.

Pastor Maldonado turned up the heat on van der Garde and Chilton with a lap of 2:03.072s pushing them both further outside the 107 per cent cut-off, and there were quicker laps still from Force India's Paul di Resta, Red Bull's Mark Webber and Sauber's Nico H?lkenberg before Hamilton and Rosberg once more reassumed control ahead of Kimi Raikkonen and Jenson Button.

Then finally at the last minute the tipping point in the track conditions was reached, and the slicks switched on with shocking effect: suddenly van der Garde, Chilton and Bianchi weren't just within the cut-off, they were into the top 16 - comfortably so at that - and through to the next round of qualifying. Those caught out in the final avalanche of fastest laps were the two Williams of Maldonado and Valtteri Bottas, both Toro Rossos of Jean-Eric Vergne and Daniel Ricciardo, and the Sauber of Esteban Guti?rrez along with Caterham's Charles Pic.

Ending up at the top of the times in Q1 was the Ferrari of Fernando Alonso who had succeeded in posting a lap of 2:00.190s which was almost two seconds ahead of Lewis Hamilton. And in third place - have the smelling salts ready for this one - was Giedo van der Garde in the Caterham following that final slick-shod run. One for the Dutchman's photo album, that one.

When the cars streamed out for Q2 it seemed that dry conditions had returned and slicks were the unanimous decision for all concerned, but one look at the threatening skies moving in over the Ardennes cautioned team bosses not to take anything for granted and to get a move on before the next weather front moved in. For now, however, Mark Webber demonstrated the improvement in conditions by slashing 10s from the fastest Q1 time with a lap of 1:50.128s, which Kimi Raikkonen contemptuously cast that aside with a lap of 1:49.323s a few moments later as he was joined at the top of the timing screens by team mate Romain Grosjean, both Lotus cars running on used medium tyres.

Reassured by the knowledge that van der Garde, Chilton and Bianchi would make up half of the six cars failing to progress, some of the big names like Vettel, Hamilton and Rosberg left it late before heading out to punch in their qualifying laps. By the time the chequered flag came out, Raikkonen had been pushed out of top spot and all the way down to the edge of the top ten, at risk of failing to make Q3. But the Finn had it all under control, and hi final effort put him back on top again with a time of 1:48.296s, just ahead of Alonso, Rosberg and Webber while Jenson Button pulled off a great escape to jump into fifth place with his final effort ahead of Vettel and Grosjean while Paul di Resta put in an assured final run under pressure to make it through in eighth place ahead of Ferrari's Felipe Massa while his Force India team mate Adrian Sutil fell short and joined H?lkenberg and Sergio Perez on the outside of Q3 looking in.

Perhaps the biggest surprise of Q2 was Lewis Hamilton, who finished on the bubble only two hundredths of a second from failing to make it through, seemingly confirming that the Hungary race winner is less than entirely comfortable in the Mercedes this weekend at Spa.

As the cars came out on slicks for the start of Q3 they were saluted by the spectators raising their umbrellas, a warning that the latest pulse of rain had indeed arrived over the final corners of the track. There was a brief moment when teams considered going for a flying lap on the slicks regardless, but sanity prevailed and everyone was forced onto pit road for a change to intermediates - all save Force India's Paul di Resta, who had started on the inters in the first place. He had the circuit to itself for a few critical minutes and arguably the best the track was likely to get for the next ten minutes - all he had to do was reach out and take the prize and dare others to grab it from him.

The Scot completed his first lap and threw down the gauntlet with a time of 2:02.332s and as the other cars set out on their first flying laps the rain was only getting harder. Massa was first to step up and was nearly two seconds off the Force India's time, and the Red Bulls were even further off di Resta's pace. Nico Rosberg showed that pole was far from settled, however by posting a time of 2:02.873s to join di Resta on the provisional front row.

Di Resta couldn't improve his time any further and ended the session early back in the Force India, and sadly for the Scot the conditions were reshaping themselves one last time and drying up just in time to foil di Resta's dreams of pole glory. Rosberg was the first person force his way to the top, and then seconds later it looked as though Sebastian Vettel had timed his run to perfection to beat everyone to the top spot. And then just when it seemed the matter was decided, Lewis Hamilton crossed the line and claimed pole by almost two tenths from Vettel to make it four in a row.

It had been a breathless, action-packed qualifying session. In many ways the grid line-up after all that tumult was rather misleadingly 'normal': Hamilton and Vettel on the front row, Webber joining Rosberg on the second, Di Resta pushed down to fifth place by that last second crush of flying laps meaning he would start alongside Jenson Button. They were followed by an all-Lotus fourth row (Grosjean pipping Raikkonen) and by an all-ferrari fifth row (Alonso comfortably in charge over Massa.)

It all makes for a very interesting start to the Belgian Grand Prix on Sunday afternoon, even before the possibility of further weather-induced chaos is factored in. Not a race to miss, that's for sure.

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