CLICK: Full GP2 feature race 1 results from Spa-Francorchamps

Raffaele Marciello denied local favourite Stoffel Vandoorne a famous home victory on Saturday afternoon, as the young Italian proved too strong in the closing laps of the GP2 feature race and forced his way past to claim his first win in the feeder series.

It was the culmination of a thrilling race at the classic Spa-Francorchamps circuit, where as has so often been the case in the past so much of what transpired was dictated by the unique weather of the Ardennes region which delivered a massive soaking to the 4.352-mile, 20-turn track as if on cue.

The start of the rain had been synced to perfection with the lights going out to signal the beginning of the race, and as the cars thundered down into La Source for the first time the heavens opened. Vandoorne had managed to get a perfect getaway in the ART and went into the hairpin with the perfect line, but fellow front row man Jolyon Palmer bogged down with too much wheel spin in the DAMS and found himself swamped going into the first corner.

There was the usual barging and minor contact through La Source with several cars running wide, but everyone made it through in one piece with Mitch Evans emerging in second place ahead of Trident's Johnny Cecotto Jr., Racing Engineering's Marciello, Venezuela GP Lazarus' Mathanael Berthon and Carlin's Julian Leal in sixth. Making up multiple places through the first turns and in the run up to Les Combes was Leal's team mate Felipe Nasr who passed his championship rival Palmer to slip into seventh place ahead of Simon Trummer in the Rapax.

However by now the main concern of the drivers wasn't track position but sheer survival: as the rain escalated to truly Biblical proportions, Conor Daly went off into the gravel at Courbe Paul Frere to trigger a safety car. This was soon modified to a full red flag stoppage as the weather conditions finally become untenable, as proved by Mitch Evans spinning the Russian Time #1 out of second place behind the safety car.

The cars returned to the grid as the rain eased and finally came to a stop. When the race resumed it ran behind the safety car for two laps before the cars were released once more at the end of lap 5, at which point Vandoorne run too deep into La Source and allowed Cecotto to pass for the lead; however the Trident overran the Les Combes chicane and was told to hand back the position to Vandoorne before he was penalised for gaining an advantage by going off track.

All the time Marciello was all over the back of the lead pair, while behind him an aggressive Nasr was able to muscle his way into fourth past Berthon who was acting as something of a bottleneck for Trummer, Evans, Palmer and Rio Haryanto running behind him. Consecutive fastest laps from the race leader as he pulled out a three second lead indicated that the conditions were improving, but the plumes of water sprays visibly warned against anyone contemplating straying to slicks at this point in the race.

Cecotto was looking increasingly ragged in second and finally succumbed to a move by Marciello around the outside of the entry into Les Combes. Moments later at the exit of the chicane, Trummer finally got tired of being held up by Berthon and tried to pass on the inside, only to get blocked and make contact with the backend of Berthon's car, tipping the Venezuela GP Lazarus into a lazy spin. Berthon was able to recover the car after Trummer helped out by running into the front right hand side to point the car back in the right direction, but the contact wrecked Trummer's front wing; however, Berthon was subsequently handed a drive-thru penalty for causing the original collision meaning that both men ended well out of the points.

With Rene Binder already out of the race, the next retirement was Racing Engineering's Stefano Coletti who strayed on to the wet kerbing and spun onto the grass heading into the bus stop as he tried to pass Sergio Canamasas. Having more luck with overtaking moves was Caterham's Tom Dillmann on Russian Time's Artem Markelov to get into the top ten; Markelov pitted after that and subsequently got into an extended knife fight for 11th position with Canamasas which finally went the Russian's way.

Palmer and Haryanto were the first of the leaders to make their mandatory pit stops at the end of lap 14, but Vandoorne, Marciello, Cecotto and Nasr were all holding out in case conditions improved sufficiently to allow them to move to slicks in the closing laps. By the end of lap 17 ART decided that the track wasn't drying fast enough and that they could bring in the race leader for a new set of wet weather tyres; Trident and Carlin decided likewise for Cecotto and Nasr leaving Marciello in charge, and he pulled out all the stops to effect the crossover before he had to come in himself two laps down the line.

When the pit stops had all played out, Vandoorne was back in front ahead of Marciello, Cecotto, Nasr, Evans, Palmer, Markelov and Negrao. However it was clear that the balance of power between Vandoorne and Marciello had been transformed, the Italian wiping out Vandoorne's lead and coming close to overtaking him into La Source and Les Combes at the start of lap 22. Vandoorne held him off that time, but on the next lap coming down the hill it was game over for the Belgian who was finally shown a clean pair of heels by the clearly superior Racing Engineering car.

There was no way back for Vandoorne who could only sit and watch as Marciello crossed the finish line two seconds ahead of him to pick up his first GP2 Series victory. The pair were in a class of their own, Cecotto half a minute further back in third after surviving a lairy moment through Blanchimont on his final lap. Nasr held on to fourth place ahead of Evans while Palmer put his title hopes first in a conservative run to the flag in sixth place ahead of an impressive Markelov who was seventh despite having been made to start from the pit lane.

There was one late retirement when Haryanto went off in the final sector, and a more significant development on the penultimate lap when Andre Negrao got loose through the bus stop on cooked tyres and nearly spun out at the pit lane entrance, which allowed Hilmer Motorsport's Daniel Abt to slip through for the position. Crucially that was for eighth place, which means that the German picks up the pole position for Sunday morning's race under reverse grid rules.

The 18-lap sprint will get underway at 10.35am (9.35am BST), and will be shown live in the UK on Sky Sports F1.

See full GP2 feature race 1 results from Spa-Francorchamps