From the track, the Marina Bay street circuit looks like a modern high-security prison: concrete walls topped off with strong mesh fencing and arc lights are, frankly, unattractive. The undulations in the track, aggravated by the number of heavy vehicles that, surprisingly, drive through Singapore daily - including the accumulation of years of city-centre construction with the massively heavy equipment that entails - cause cars to be travelling at high speeds over what is, at points, almost like corrugated iron. There are almost two dozen corners - some severe and some almost straight - that pop out from behind those concrete walls, and artificial chicanes with low but severe kerbs that are invisible to the driver until he is almost on them. Road markings add to the hazards (slippery when wet or dusty and distracting as they appear and disappear in peripheral vision. There is no opportunity to drive the track, in its race configuration before practice starts. And the track has been modified in a number of important ways since last year, including new entrance to and exit from the pit lane to facilitate easier and safer bleeding into and out of traffic.

Humidity is a major factor in this track which is just 70 miles from the equator and operates at an elevation of effectively zero above sea level at high tide. The elevation, or lack of it, means denser air for the engines and that equates to more power. But the chance to use that power is limited - there isn't much straight-line running here.

The threat of heavy rain is ever present. And Singapore has been due a downpour for several days. Then there is the question of so-called "haze." This is smoke, sometimes chokingly dense, that drifts over from Indonesia - visible from Singapore with a decent pair of binoculars. Inside a helmet, eyes sting and airways burn. So far this week, there has been little smoke as the burning season (illegal but nevertheless widespread) is coming to an end.

The concrete walls are unforgiving - much more so than the Armcos that line tracks such as Monaco and Macau. And because this is a true street-race, the roads are only as wide as roads can be, meaning that there are very few tyre or other deformable barriers. Here, a small accident turns into a big one very quickly, and light damage is rare; a small error turns into a major crash with alarming alacrity.

On Friday, Webber had an accident that, on other tracks would have been minor: here he needed serious remedial work. If there is a track anywhere that the wheels are going to be knocked off, it's Singapore: and the number of wheels that came off in practice was disturbing.

The track is considered to be a high downforce track because of its short straights and many corners. A premium is put on grip. It's a simple equation: too little grip equals a crash. There is very little in between. But grip is compromised. Although teams run cars with softer suspension than at many tracks (softer suspension not only damps vertical movement, it also increases the area of the tyres that are in contact with the road as the cars switch from left corner to right corner) what F1 calls "soft" is still like someone sticking blocks of wood in your road-car suspension.

Downforce comes from the body work and its appendages: but it also comes from sucking the car to the road - and for that to be effective, the ride height has to be as low as possible. That's fine on smooth track, but where cars drive through what is, normally, an extremely busy interchange, there are crests and troughs. The cars hit those crests so hard that, despite the wooden board that must remain at a minimum thickness, metal parts of the car hit the road, creating rooster-tails of sparks.

And every bump feeds directly into the bum and back of the driver, jarring his neck and, in extreme cases, blurring his vision. The effect is that of turning the weekend into an endurance event: who can stand the physical punishment and keep his mental faculties operating at peak performance, who can drive to within millimetres of the wall, lap after lap, and - because so little can be seen from the cockpit, who remembers the circuit best and can place his car in the correct position before he can see the corner or chicane. And do all of that while listening to his team and watching for warning lights telling of crashes that are out of sight.

And every bump, and every kerb ridden over, lifts the car, undermines the mechanical grip, and makes it skittish, at speed looking like a badly driven Scalectrix car fishtailing out of every corner.

Overlaid on this is the fact that the track is dusty and "green" - that is that there is not much rubber on it, the fact that, as a public road, there is the danger of a thin oil film which is particularly dangerous in the event of the slightest drizzle.

Into all of this come the world's best drivers - some of which are unfairly being seen as also rans. The track magnifies differences: the bravest - one might almost say the most foolhardy - will benefit provided they don't get caught up in someone else's accident.

Before qualifying, Lewis Hamilton expressed his concern over the track saying that increased kerb height at Turn 10 risked damage to cars (failing to realise that the solution is not to ride the kerbs). He said that surface improvements had not made much difference "The car is bumping and bouncing and sliding. It's still very bad. I don't really think it's changed at all to be honest."

In practice, the Brawn cars behaved well: in qualifying they did not. Changes to Button's car - which was consistently amongst the fasted in practice, turned it into an evil handling monster, dumping him into a distressing 12th on the grid. His team mate, at least made it into Q3, finishing fifth. But that will be undone by the expected change of gearbox: a penalty of five places puts him tenth.

Ironically, that puts Button in a better position. Rubens Barrichello says that his car handled much better on a heavier fuel load, and that the light running in Q2 handicapped the team's cars. Barrichello will have to start directly in front of Button, both on the dirtier side of the track with the fuel load he used in qualifying. Button, on the other hand, will have the advantage of choosing his fuel level. Logic says he will start fully fuelled and on hard tyres, sacrificing initial pace for a better handling car and expecting at least one safety-car session.

The safety car may well come out after the first corner which has been remodelled and now creates an even more dramatic funnelling effect than in 2009.

Button and Barrichello have both made one thing extremely clear: there are no team order and they don't expect there to be. Ross Brawn, their team leader has said the same. For Button he has special worry: in several races this year, his team-mate has been desperately slow off the line with a number of niggling problems ranging from electronics to gearbox. Button will probably prefer to follow Rubens through the traffic rather than be forced into a risky start-line move - or being hit from behind by another car. For Brawn, then, the worst case scenario is that Barrichello doesn't get away, and both cars are wrecked in a concertina accident, or come together in the funnel into Turn One.

Up at the pointy end, Hamilton skated his way to pole, just ahead of Vettel whose team-mate Webber fourth. The Force India team languish at the bottom, their low-downforce, high straight-line speed car effectively handicapped out of contention.

It was Williams that surprised: Nakajima turned in a surprising 11th, but it was his team-mate, Rosberg, who raised eyebrows with his third place. Rosberg drove a storming race last year to finish second behind Alonso - something he has this week said was unfair and that Alonso's win should have been taken away.

Almost as incredible as the Williams positions are those for BMW Sauber. The team that is, currently, out of Formula One for next year has produced a car that suits Singapore much more than many other tracks in the series: Heidfeld, still trying to demonstrate the form that he was said to have when he came into F1 and his team-mate Kubica, whose flashes of genius when he arrived in the sport now smack of being flashes in the pan, were 8th and 9th respectively.

Those that question Button, and there are many who are pointing fingers and saying he doesn't have the mettle to win the championship, are not noticing that the much vaunted Ferrari revival has put Raikkonen behind button. They are also not noticing that that Button's Q2 time was more than half a second faster than Hamilton's eventual pole, nor that Kovalainen's 10th on the grid (promoted to 9th by Rubens' penalty) was actually the slowest time of all the qualifying runs in all three sessions.

Apparently, then, McLaren have run a split strategy: Hamilton light, Kovalainen heavy.

Glock found himself mixing it with the big boys: he ended up 7th, moved up to 6th, whilst his team-mate Trulli, a low-downforce, late braking specialist - found himself 15th. Sutil will have been utterly disappointed with 16th: after recent performances to fail to make it out of Q1 will have been disheartening.

But he has bigger problems that his feelings: he's down amongst all the new drivers: Fisichella can't get to grips with the Ferrari, Grosjean, Algersusari and Liuzzi are too new to Formula One to cope with the rigours of the Singapore event. But those factors will turn them all into opportunists, particularly off the line. If anyone is slow away, the ensuing concertina will bring those rear-of-field drivers up to the back of the pack with startling speed.

The difference between the fastest and slowest (flying) laps in qualifying was just 3.2 seconds; the difference between the eventual pole and the back of the field was just 1.1 seconds. There is more than 2 seconds between pole and tenth.

But the post-qualifying presumptions on fuel loads have been annulled by the FIA's figures, released this morning.

Rubens was running light - some 28kg lighter than Button. But the McLarens were similarly fuelled: Kovalainen just 5kg heavier than Hamilton who was 5kg heavier than Barrichello.

Running heavy are Button, Grosjean, Sutil, Trulli, Raikkonen and Nakajima.

It's Sutil who is heaviest: 38kg heavier than Hamilton suggesting that he is considering a one-stop strategy which will be possible if there are two safety car incidents.

Barichello upset the applecart for several drivers who were clearly banking on a last minute dash to the line: with 24 seconds to go, just as cars were doing their last dash or their final run to cross the start line immediately before the flag fell, Rubens hit the wall and the session was stopped. That nevertheless retained his fifth fastest position which was under threat and also preserved Hamilton's pole - although Hamilton said that he had expected to do an even quicker lap as his pole lap was "very relaxed." Watching his car barely in contact with the road, it certainly did not look relaxed.

For Barichello and Button, however, they are in a bind: a win for Vettell and no points for Rubens will bring Vettel close to second place in the championship. They need to score points. If Button is, as he has been in recent weeks, punted off at the start, then Rubens will close up on him - bringing him within striking difference in the last three races.

Barichello's last minute accident obviously upset the strategy of those in Q3 who were planning to run light to get the best time, including Kovalainen. Vettel had saved a new set of tyres for one last run - and lost that due to the stoppage.

It was half-expected that Rubens would struggle for grip: he had hit a kerb too hard in Q2 and damaged the underside of the car, so reducing grip. As the car bounced off a bump part way through his last lap in qualifying, it was barely in contact with the ground as he tried to turn: and inevitably it didn't, then when it came into full contact with the road, it turned unpredictably.

In 2007, Hamilton went into the last four races with a 17 point lead, and lost the endgame. Button's lead over his team-mate at just 14 points is more precarious.

That all of these factors will come to a head this evening means that the Singapore GP 2009 will be an event of drama and tension.

The Singapore weather bureau is showing early afternoon thunder and rain in the north and west of the island. Word from our office in Kuala Lumpur, just 300 km north, is that right now, seven hours before the race starts, there are heavy clouds and thunder and lightning with high winds and heavy rain moving from the west.

There are support races in the early afternoon but no "morning" warm up. The first time today the F1 drivers see the track is as they drive to the grid for the formation lap. And most of the rubber that has been previously laid may well have been washed away by the time they do that.

The final factor that makes the GP even more fascinating may well be the weather.

For F1 has never run a night race in the rain, and has tried hard to avoid street circuits that are likely to be wet. US race series habitually cancel races in the wet, particularly at night.

The drama of the Singapore GP has much to play out.