Belgian teams WRT Audi and Marc VDS BMW have shown the way in a crash-marred opening half of the Spa 24 Hours.
The trio are locked in a battle with the #77 Marc VDS BMW of Lucas Luhr/Markus Paltalla/Dirk Werner and the second WRT entry of James Nash/Frank Stippler/Christopher Mies, which are currently the only cars on the lead lap.
The Sainteloc Audi of Edward Sanstrom/Stephane Ortelli/Gregory Guilvert and third WRT Audi of Marcel Fassler/Andre Lotterer/Benoit Treluyer completed the top five.
The car remains in strong contention for a podium in the Pro-Am class, which is being led by the #90 Scuderia Villoba Corse Ferrari.
The incident was one of several frightening crashes that dominated the opening four hours.
Russian driver Vyacheslav Maleev was the first to strike major trouble when he trashed the SMP Ferrari at Eau Rouge early in the second hour.
That incident was followed almost immediately by Mullen's crash at Blanchimont.
Karim Ojjeh was the next to find the barriers at Eau Rouge in the Boutsen McLaren, before Andrew Howard (Beechdean Aston), Andrew Danyliw (AF Corse Ferrari), Tim Muller (Rinaldi Ferrari) and Alex Demirdjian (Boutsen McLarens) were all taken out in a multi-car incident at the same corner.
A further collision between Marcus Mahy (Kessel Ferrari, co-driven by Australian Liam Talbot) and Vadim Kogay (Rinaldi Ferrari) at Stavelot then saw the red flags called during the fifth hour, enabling Mahy to be air-lifted to hospital.
With the clock continuing to run under the stoppage, the entire sixth hour was spent either under red or yellow flag conditions.
The race settled down when green flag action returned in Hour 7, with the lead changing between the top German-built cars as each hourly pitstop cycle unfolded.
The ninth hour saw the retirement of Marc VDS's second BMW, shared by Maxime Martin/Jorge Muller/Augusto Farus, after it hit a rabbit.
The all-Australian Lago Racing Lamborghini holds down a top 30 position at halfway, albeit over 10 laps down on the outright leaders.
Australian GT Championship leader Richard Muscat is also mid-field; the Pro-AM Black Falcon Mercedes 25th at time of writing with German Christian Bracke at the wheel.
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