The Manthey Porsche squad led the Spa 24 Hours at three-quarter distance by just four tenths of a second.
The German team's Porsche 911 GT3-R driven by Marc Lieb, Richard Lietz and Patrick Pilet was fighting a rear-guard action to hold off the HTP Motorsport Mercedes-Benz SLS AMG shared by Bernd Schneider, Maximilian Gotz and Maximilian Buhk at the 18-hour point of the blue-riband round of the Blancpain Endurance Series.
The Porsche was, however, due a pitstop, which came just after the hour and restored a true gap of just over two minutes.
That gap came courtesy of a quicker brake change for the Mercedes, which made its stop for new pads and discs in the 11th hour, while Manthey undertook a similar service in the 13th hour.
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The two German machines were the only two cars on the lead lap after the remaining of the trio of Marc VDS Racing BMW Z4s went out in the 13th hour when a freak failure of the cockpit fire extinguisher damaged the wiring loom.
The best Audi R8 LMS ultra, the solo remaining car from the Belgian WRT squad's four-car entry, held third place in the hands of Andre Lotterer, Frank Stippler and Christopher Mies.
Foruth place was held by the championship-leading trio of Davide Rigon, Daniel Zampieri and Cesar Ramos aboard the Kessel Racing Ferrari 458 Italia.
The Pro-Am class was led by AF Corse Ferrari shared by Toni Vilander, Matt Griffin, Duncan Hamilton and Alex Mortimer.