Hello and welcome to Spa Francorchamps for the final session of practice ahead of this afternoon's qualifying session.

It is dry at the moment, here's the latest weather update from Lotus' Mike Gascoyne: "Still no rain and no showers on the radar and the track is dry but still a few damp patches off line. Session will start dry. Still chances of rain increasing towards qualifying"

The first two practice sessions were rain-affected but we did get some dry running towards the end of second practice. Alonso topped both sessions and goes into today's qualifying session in a buoyant mood.

Images around the circuit shows that there are in fact still a few wet patches, probably still a bit too damp for slicks.

An update from Force India, whose Adrian Sutil was second fastets yesterday: "We'll be running blown diffusers on both cars. Weather forecast says 50% chance of rain so could do anything..."

The session has started and a gaggle of car is filtering out of the pits on very worn intermediate tyres.

Jarno Trulli leads the cars out. Senna has gone out on slick tyres and is talking us around the track in his HRT over the radio.

Correction: A lot of the cars did head out on slick tyres - Alonso is out on them now in the Ferrari. Of course, nobody is really pushing yet these are installation laps to check that the systems on the car are still working.

Schumacher is out on track on intermediate tyres.

All the drivers have completed an installation lap and have returned to the pits. We might have a bit of wait for the frontrunners to go out again as they wait for the track conditions to improve.

De la Rosa reports that there is generally a dry line out on track at the moment.

Ferrari reports: "According to the drivers there are still some damp patches here and there, especially where there is still shadow."

Felipe Massa is sat in the back of the garage at the moment.

Schumacher leaves the pits n hard slick tyres, as does Buemi and di Grassi.

Schumacher is fairly tentative out there, dropping a couple of gears through Pouhon.

Plenty of button pressing and hand movement going on in the cockpit of Schumacher's Mercedes. The rumour is that that is to operate F-duct. And he is told it is working well.

Buemi sets a 1:50.108, the fastest time so far, Schumacher is 3 seconds off that.

Hamilton is now on a fast lap... he sets a 1:48.069, 0.4s up on Hulkenberg.

Vettel goes through Eau Rouge one handed as he operates his F-duct. Very brave.

Vettel sets the fastest time with a 1:47.472.

Button is heavily blocked on his flying lap behind Trulli, nothing wrong with that as it's only a practice session, but the McLaren aborts a fast lap as a result.

Kubica is now the quickest driver on track with a 1:46.492.

Lotus expects rain in 15 minutes: "Brief shower at 11.40 for a few mins"

Hamilton is now fastest with a 1:46.315, he's now on his eighth lap of this run.

Button is back out and is now sixth fastest with a 1L47.369.

Alonso goes third fastest but is about 0.7 off Hamilton at the moment.

Hamilton sets another fastest lap as he notches up his ninth lap of this run. We have no idea exactly what fuel loads they are running but I expect they are fairly heavy right now.

Both Renaults have switched to soft tyres to ensure they get some running ahead of the predicted rain in 10 minutes.

Webber is now out on track and pushing quite hard behind the wheel of that Red Bull. He is currently fastest through the second sector. Webber is 0.217 off Hamilton.

Liuzzi has only completed one lap this session and reports from the pits suggest the team has removed the F-duct from that car. That seems like a strange decision at this stage of the weekend.

Webber goes fastest with a 1:46.106, a better first sector on that lap.

Ferrari says: "The shower could be reasonably heavy, it's a matter of minutes." Most drivers are now out on soft tyres.

Vettel is on a fast lap but is now being held up by a Sauber. Button has set a fastest first sector on his last lap.

Vettel's time is only good enough for third, 0.3s down on Webber. However, he was held up by Kobayashi quite badly.

Button goes fourth fastest with a 1:46.397. Massa runs wide and ruins his lap at turn 13.

Hamilton is 0.117 seconds off Webber, there isn't much in it.

Vettel has nearly come to a standstill in the pit lane. The dashboard of that Red Bull is flashing away furiously. Obviously a loss a drive from his Renault engine, not sure exactly what the problem is.

Red Bull boss Christian Horner says he has no idea what went wrong so it was an unexpected failure that the team did not spot on the telemetry.

Rain is coming down over the pit and paddock area but it's still fairly dry at the top of the circuit.

The engine cover is off Vettel's Red Bull as the rain buckets down over the pit lane.

So the track is now empty. Down at Red Bull they have the engine fired back up but it could be a hydraulic problem for Vettel.

Hamilton is out of his car and that looks as though he won't be going back out again.

Alguersuari has gone back out on track in the rain to get a bit of wet weather practice in. He is out on full wet tyres.

Schumacher is now out on track in the Mercedes, again on full wet tyres.

Vettel is now back out on track so the problem with that Red Bull is obviously fixed.

Five cars are out on track, Vettel has returned to the pits after his brief run.

Vettel is now out of the car and won't go back out again, so it's going to be a rather anticlimactic end to this session.

Button is starting one last flying lap in the McLaren on intermediate tyres.

Hamilton is also out on track as the chequered flag falls.

Ferrari offers an explanation for the sudden rush of cars: "Many people are going out now to have the opportunity of the practice start on the grid"

Unsurprisingly, Button is about 17 seconds off the pace on his wet weather lap.

Thank you for joining us for this session. It looks very tight at the top of the timesheets, make sure you join us for qualifying this afternoon to find out who will start from that all-important pole position.