Pier Guidi, Come Ledogar and Nicklas Nielsen took honours in the #51 Ferrari 488 GT3 that had led most of the race by 3.978 seconds ahead of the #32 Audi R8 LMS GT3 of Vanthoor, Charles Weerts and Kelvin van der Linde.
Pier Guidi went around the outside of Vanthoor at the fast Blanchimont left-hander to reclaim the lead with 10 minutes to go, having lost out when WRT rolled the dice with storm clouds looming and sent Vanthoor out on wet-weather tyres before it had started to rain with 50 minutes on the clock.
The downpour arrived on the Belgian driver’s outlap and then Iron Lynx opted not to bring in Pier Guidi at the first opportunity. By the time the Italian had completed a slow lap on a flooded track and changed to grooved Pirellis, the Italian had fallen 50s behind the Audi.
A Full Course Yellow had already been called and when the safety car bunched the field up, Pier Guidi was little more than three seconds behind when the race went green for the final 27 minutes.
The Ferrari quickly closed down the the Audi and was right with the German car inside five laps. He was only half a second behind starting the 551st lap and then got a better run out of Stavelot and braved it out around the outside through Blanchimont at the end of the lap.
Pier Guidi was able to extend the lead over the remaining laps to five seconds, before crossing the line 3.9s ahead.
It marks the first win for a Ferrari in the Spa 24 Hours in the GT3 era and the Scuderia’s first since 2004, as well as the brand’s fourth victory overall.
“I’ve been trying so many times to win this race, I really wanted it, really, really,” said Pier Guidi. “When the rain came and everything seemed lost, I was really disappointed. I pushed like an animal and I did all I could.”
It was a sweet victory for Iron Lynx on its debut in the Spa enduro after the Italian team had lost a car in the opening hour when Davide Rigon was involved in a four-car accident at Eau Rouge.
The accident resulted in Rigon and Williams Formula 1 reserve driver Jack Aitken, who triggered the incident when he spun his Emil Frey Lamborghini at Eau Rouge, being taken to hospital in nearby Liege.
Rigon was released after undergoing tests, while Aitken was diagnosed with fractures of a vertebra and his collarbone.
Aston Martin claimed third place with the all-factory line-up of Nicki Thiim, Marco Sorensen and Ross Gunn in the Garage 59 team’s Pro class entry more than a minute in arrears of the winning Ferrari.
They never made up the ground they lost during the night when they made their technical pitstop, a mandatory four-minute stay in the pits to allow for a change of brakes, under green conditions unlike the majority of their rivals at the front of the field.
The second of the factory Audis run by WRT driven by Nico Muller, Robin Frijns and Dennis Lind took fourth position two laps behind.
Nick Tandy, Maxime Martin and Laurens Vanthoor, who had to sit out much of the second half of the race after an accident in the paddock, took fifth in their KCMG Porsche 911 GT3 R in what was largely a miserable race for the defending champion marque.
The factory-backed Sainteloc Audi shared by Markus Winkelhock, Christopher Haase and Patric Niederhauser rounded out the top six, ahead of the JOTA McLaren 720S GT3 and the FFF Racing Lamborghini Huracan GT3 that dropped out of lead contention with a series of penalties.
Silver Cup honours went to the Madpanda Mercedes-AMG GT3 driven by Ezequiel Perez Companc, Ricardo Sanchez, Patrick Kujala and Rik Breukers that finished 11th overall.
AF Corse Ferrari drivers Duncan Cameron, Rino Mastronardi, Matt Griffin, Miguel Molina came out top in the Pro-Am class and 16th overall.
Race results (top 10):
Alessandro Pier Guidi
Ferrari 488 GT3
Kelvin van der Linde
Audi R8 LMS GT3
Aston Martin Vantage GT3
Audi R8 LMS GT3
Porsche 911 GT3 R
Audi R8 LMS GT3
McLaren 720S GT3
Lamborghini Huracan GT3
Audi R8 LMS