Audi trio Oliver Jarvis, Lucas di Grassi, and Loic Duval emerged from a chaotic WEC 6 Hours of Spa with an unlikely victory, as the German marque's LMP1 rivals Porsche and Toyota both hit trouble.

It was a maiden WEC victory for Jarvis and Di Grassi, and Duval's first since 2013, as Audi secured its first win in the series since last year's Spa race after its exclusion from victory at Silverstone.

With the R18 e-tron quattro running its Le Mans-style low-downforce package at Spa, Audi lacked race pace and had to rely on Porsche and Toyota hitting trouble with both cars to take the win.

Just like at Silverstone, it was Porsche that controlled the early stages, as the #1 919 Hybrid of Brendon Hartley raced to an early lead ahead of the #2 of Marc Lieb.

But the German was hit early on by a hybrid failure that caused him to start lapping several seconds off the pace, dropping behind both Audis and Toyotas.

The #5 Toyota TS050 Hybrid of Sebastien Buemi soon emerged as Hartley's main challenger, battling his way past Benoit Treluyer's #7 Audi in a superb scrap during the opening hour.

Treluyer became the second of the LMP1 runners to hit trouble however when the #7 sustained floor damage from debris, losing time with in numerous trips to the pits.

Toyota takes charge as Porsche falters

The #5 Toyota took the lead at the end of the first hour as the team chose to double stint its tyres, allowing Buemi to rejoin 20 seconds clear of Hartley when the #1 Porsche came for its first stop.

Timo Bernhard took over from Hartley, and was catching Buemi before sustaining a front-left puncture, costing the #1 precious time.

Some 20 minutes later, Bernhard suffered another puncture, before the #1 dropped to the rear of the field with a lengthy stop to change the front gearbox mechanism some time later.

That left the #5 Toyota with a comfortable advantage over the #8 Audi in second, and such was the pace of the TS050 Hybrid that it was able to put a lap on the R18 by the end of the fourth hour.

By that stage, the #6 Toyota, which had been running a relatively distant third after Mike Conway was delayed by a collision with the #37 BR01 at the Bus Stop chicane early on, had dropped out with an electronics failure.

Shortly into the fifth hour, Kazuki Nakajima was forced to bring in the leading #6 car into the pits with an engine failure after smoke began to billow from the rear of the car, bringing Toyota's day to a premature end.

Audi has late scare after huge Ford crash

With both Toyotas out, the #8 Audi assumed a lead of three laps over the #2 Porsche, although there was late drama when the Safety Car was deployed following a monster shunt for Stefan Mucke's #66 Ford GT at the top of Eau Rouge with a little over an hour to go.

Despite clouting the tyre barriers at barely abated speed after a left-rear tyre failure, Mucke escaped with nothing more than bruising.

Shortly after, Audi brought the #8 car into the pits for a precautionary change of rear bodywork, Jarvis then bringing home the R18 e-tron quattro in the final hour with a two-lap advantage over Romain Dumas in the #2 Porsche.

Rebellion trio Alexandre Imperatori, Matheo Tuscher and Dominik Kraihamer took the bottom step of the overall podium after enjoying a largely trouble-free run in the #13 R-One, four laps down on the winning Audi and a lap ahead of the sister #12 machine.

The #7 Audi was only a further six seconds back at the flag, and had been firmly on course to catch the #12 Rebellion before Marcel Fassler made contact with the #43 Ligier at La Source, brushing the barriers in the process.

The top six was completed by the #4 ByKolles CLM, which finished nine laps down.

Signatech wins frantic LMP2 battle

Mucke's crash turned the battle for LMP2 honours into a frantic final-hour shootout, as the top four were all brought nose-to-tail.

The #36 Signatech Alpine of Nicolas Lapierre, Gustavo Menezes and Stephane Richelmi had assumed the lead in the fourth hour when the class-leading #44 Manor Oreca hit trouble with an apparent brake problem.

Lapierre was forced to stave off a spirited late challenge from Pipo Derani in the #31 ESM Ligier, with the trio swapping positions while negotiating traffic - the pair at one stage going three-wide with the sole surviving #67 Ford at Fagnes.

In the end, Lapierre held on by four seconds to seal Signatech's victory, with Derani taking second for ESM just clear of the surviving #45 Manor of Roberto Merhi and Albuquerque in the #43 RGR Sport by Morand Ligier.

The #26 G-Drive Oreca came fifth, but had dominated the early stages before suffering a puncture that lost the car a lap.

G-Drive's second entry, the #38 Gibson, was sixth after recovering from a two-minute stop-and-go penalty for a collision with the #95 Aston Martin.

The contact at Stavelot between Simon Dolan in the #38 and Nicki Thiim in the Aston resulted in a backwards spin for the Dane that caused the Vantage to flip over and land right-side up.

Ferrari unstoppable in GTE

The GTE class was led from start to finish by the AF Corse Ferraris, but there was a late sting in the tail for Gianmaria Bruni and James Calado when the #51 488 Italia was forced to head for the garage in the final 10 minutes.

That meant the #71 car of Davide Rigon and Sam Bird took a second consecutive class victory, a lap ahead of the #67 Ford of Andy Priaulx, Marino Franchitti and Harry Tincknell.

The #66 car had already dropped out of podium contention with a turbo failure before Mucke's crash.

Aston Martin's sole surviving #97 entry completed the class podium in third place, while the #98 car of Pedro Lamy, Paul Dalla Lana and Mathias Lauda benefitted from the late safety car period to pass the #83 AF Corse Ferrari for victory in GTE-Am.

Race results:

Pos Driver Car Time
FranceLoic Duval 
United KingdomOliver Jarvis 
BrazilLucas di Grassi 
Audi R18 E-Tron Quattro '16  6:032.112 
GermanyMarc Lieb 
FranceRomain Dumas 
SwitzerlandNeel Jani 
Porsche 919 Hybrid '16  +2 laps 
SwitzerlandAlexandre Imperatori 
SwitzerlandMatheo Tuscher 
AustriaDominik Kraihamer 
Rebellion R-One  +4 laps 
BrazilNelson Piquet Jr. 
GermanyNick Heidfeld 
FranceNicolas Prost 
Rebellion R-One  +5 laps 
GermanyAndre Lotterer 
FranceBenoit Tréluyer 
SwitzerlandMarcel Fassler 
Audi R18 E-Tron Quattro '16  +5 laps 
United KingdomJames Rossiter 
United KingdomOliver Webb 
SwitzerlandSimon Trummer 
CLM P1/01  +9 laps 
FranceNicolas Lapierre 
United StatesGustavo Menezes 
MonacoStéphane Richelmi 
Alpine A460  +9 laps 
United KingdomRyan Dalziel 
BrazilPipo Derani 
CanadaChris Cumming 
Ligier JS P2  +9 laps 
SpainRoberto Merhi 
United KingdomMatt Rao  
United KingdomRichard Bradley 
ORECA 05  +9 laps 
10  MexicoRicardo Gonzalez 
PortugalFilipe Albuquerque 
BrazilBruno Senna 
Ligier JS P2  +9 laps 
11  RussiaRoman Rusinov 
GermanyRené Rast 
FranceNathanael Berthon 
ORECA 05  +10 laps 
12  United KingdomSimon Dolan 
NetherlandsGiedo van der Garde 
United KingdomJake Dennis 
Gibson 015S  +12 laps 
13  United StatesScott Sharp 
United StatesEd Brown 
United StatesJohannes van Overbeek 
Ligier JS P2  +14 laps 
14  ItalyDavide Rigon 
United KingdomSam Bird 
Ferrari 488 GTE  +15 laps 
15  ThailandTor Graves 
United KingdomWill Stevens 
United KingdomJames Jakes 
ORECA 05  +16 laps 
16  United KingdomAndy Priaulx 
United KingdomMarino Franchitti 
United KingdomHarry Tincknell 
Ford GT '16  +16 laps 
17  United KingdomJonathan Adam 
New ZealandRichie Stanaway 
BrazilFernando Rees 
Aston Martin Vantage V8  +16 laps 
18  AustriaRichard Lietz 
DenmarkMichael Christensen 
Porsche 911 RSR  +18 laps 
19  PortugalPedro Lamy 
CanadaPaul Dalla Lana 
AustriaMathias Lauda 
Aston Martin Vantage V8  +20 laps 
20  FranceEmmanuel Collard 
PortugalRui Aguas 
FranceFrançois Perrodo 
Ferrari F458 Italia  +21 laps 
21  ItalyPaolo Ruberti 
JapanYutaka Yamagishi 
FrancePierre Ragues 
Chevrolet Corvette C7 GT3  +21 laps 
22  GermanyChristian Ried 
SwitzerlandJoel Camathias 
GermanyWolf Henzler 
Porsche 911 RSR  +21 laps 
23  United KingdomMike Wainwright  
United KingdomAdam Carroll 
United KingdomBen Barker 
Porsche 911 RSR  +22 laps 
24  RussiaVitaly Petrov 
RussiaKirill Ladygin 
RussiaViktor Shaytar 
BR Engineering BR01  +24 laps 
25  United Arab EmiratesKhaled Al Qubaisi 
DenmarkDavid Heinemeier Hansson
United StatesPatrick Long 
Porsche 911 RSR  +24 laps 
26  United KingdomAnthony Davidson 
JapanKazuki Nakajima 
SwitzerlandSébastien Buemi 
Toyota TS050 HYBRID  +46 laps 
27  AustraliaMark Webber 
New ZealandBrendon Hartley 
GermanyTimo Bernhard 
Porsche 919 Hybrid '16  +48 laps 
R Nelson Panciatici 
Ho-Pin Tung 
David Cheng 
Alpine A460  
R Gianmaria Bruni 
James Calado 
Ferrari 488 GTE  
R RussiaDevi Markozov  
Nicolas Minassian 
Maurizio Mediani 
BR Engineering BR01  
R Billy Johnson 
Olivier Pla 
Stefan Mücke 
Ford GT '16  
R Kamui Kobayashi 
Mike Conway 
Stéphane Sarrazin 
Toyota TS050 HYBRID  
R Jonny Kane 
Nick Leventis 
Danny Watts 
Gibson 015S  
R Nicki Thiim 
Marco Sorensen 
Darren Turner 
Aston Martin Vantage V8

Gallery: Spa WEC: Audi survives mayhem to clinch unlikely victory