Ahead of today's practice session, the air temperature is 12 degrees C, while the track temperature is 20 degrees. Though it is bright, there is a 20% chance of rain. Indeed, there was rain overnight and again first thing this morning.

Ferrari topped the timesheets in both of yesterday's session, Sebastian Vettel in the morning and Kimi Raikkonen - a four-time winner here - in the afternoon. However, the German didn't get a clean run on the softest compound in the afternoon.

Mercedes was strong - its drivers, like those at Ferrari, enjoying an engine upgrade - though Valtteri Bottas will start from the back of the after taking on his fourth power unit of the season.

Following a fraught morning which saw him only complete one lap, things were better in the afternoon for Daniel Ricciardo, while Max Verstappen had a largely trouble-free day.

Despite their many and varied issues, Force India was best of the rest, with Sergio Perez seventh quickest, though Ocon had a difficult afternoon having to rely on one set of supers following a puncture.

Looking particular strong were the Sauber pair, who finished ninth and tenth.

No sooner have the lights gone green than Ericsson and Grosjean are hitting the track, followed by Gasly, Hartley and Vandoorne, who had a tough day yesterday.

As most complete an installation lap before pitting, Alonso posts the first time of the day, the Spaniard stopping the clock at 47.202. Vandoorne subsequently posts 2:06.382.

While softs and mediums are the order of the day, the Ferrari pair head out on supers, the first drivers to do so.

Alonso improves to 46.942 and Vandoorne 47.163 as Hulkenberg becomes the third driver to post a time (50.159).

Raikkonen goes quickest with a 43.425 while Vettel can only manage 45.106, the German losing time behind countryman Hulkenberg who is running his own programme.

Vandoorne is told that while T12 is good compared to yesterday, he can do better.

A 46.555 sees Sainz go third ahead of Alonso, Vandoorne and Hulkenberg.

Having gone quickest in S1, Raikkonen becomes embroiled in a battle with... wait for it, Hulkenberg. The German blocks the Finn but The Iceman nails him at the final chicane.

Hulkenberg - who will also start from the back of the grid tomorrow - is warned that he's on the limit in terms of tyre temperatures.

Finally, Vettel gets a clean lap (43.869), but remains 0.444s shy of his teammate.

On the softs, Bottas posts43.942 to go third, as teammate Hamilton heads out, also on softs.

Quickest in the first two sectors, Hamilton loses time in S3, crossing the line at 43.523, just 0.098s down on Raikkonen.

Ocon goes fifth with a 45.485 as, 24 minutes into the session, Ricciardo is the first of the Bulls to head out.

From fifth (Ocon) to tenth (Magnussen) it's less than a second.

Ricciardo goes sixth with a 45.242, the Australian on the supers.

Indeed, more and more drivers are switching to the red-banded rubber now.

Alonso misses the chicane at Les Combes.

Verstappen goes 5th with a 44.399 on the softs, albeit 0.974s down Raikkonen.

Switching to the supers, Bottas goes quickest in S2 and despite a poor final sector goes second with a 43.492, just 0.067s down on Raikkonen.

Yet to try the softest rubber, the McLaren pair are currently 19th and 20th, both over 3s off the pace.

Vettel improves to second but still remains 0.033s off Kimi's stellar lap. Hamilton also improves but remains third and a tantalising 0.064s off the pace.

Hamilton complains of a vibration on his current set of tyres.

A strong opening sector from Raikkonen sees the Finn lose a little pace in S2 and again in S3.

PBs in the final sectors see Vettel go quickest, the German crossing the line at 42.661.

With the Bulls yet to run on the supers, Leclerc, also on softs, is currently best of the rest, ahead of Perez, Hulkenberg and Ocon.

With thirteen minutes remaining, and the qualifying sims about to begin, Raikkonen reports rain at T1.

Oh dear, out come the double yellows as the cameras pick up on Vandoorne who has gone off on the Kemmel Straight and is left facing the wrong way after a big spin and a clash with the barriers.

Replay shows the McLaren dipping a toe on the grass as he attempts to pass Bottas as they head up the hill.

The session is red-flagged.

Asked if his car is OK, Vandoorne replies: "No it is not, what the hell was that Mercedes doing, he ******* pushed me on the grass." Though the stewards are to investigate, the replay suggests otherwise.

That said, Bottas admits: "I didn't see".

All of which has really compromised - or ****** up, to use a Grosjean term - the drivers qualifying sims.

The stewards reveal that the session will re-start at 12:58, which is pretty much pointless. While there should be enough for one flying lap, the traffic will be horrendous.

The situation isn't helped when Gasly, in his enthusiasm to get out, spins at the pitlane exit.

In the garage, Vandoorne, who has had a nightmare weekend thus far, explains what happened. In FP1 he lost track time due to a brake issue, in FP2 he needed a new floor, and now this.

As the chequered flag is waved, there are 19 drivers on track.

While there are lots of green lighting up the timing screen there are no purples.

There are no significant improvements, and as the chequered flag is waved, it's: Vettel ahead of Raikkonen, Hamilton, Bottas, Verstappen, Ricciardo, Leclerc, Perez, Hulkenberg and Ocon.

Ericsson is eleventh, ahead of Grosjean, Sainz, Magnussen, Gasly, Hartley, Stroll, Sirotkin, Alonso and Vandoorne.

Check out our Saturday gallery from Spa, here.