Audi led the Spa 24 Hours at three-quarters distance with the WRT R8 LMS ultra shared by Rene Rast, Markus Winkelhock and Laurens Vanthoor.
Winkelhock held a 49-second advantage over the Marc VDS BMW Z4 in the hands of Lucas Luhr when the double-points round of the Blancpain Endurance Series hit the 18-hour mark.
The Audi and the BMW, which Luhr shares with Dirk Werner and Markus Palttala, have been swapping positions with pitstops after getting out of sequence early in the race.
Third place was held by the WRT Audi driven by three-time Le Mans 24 Hours winners Andre Lotterer, Benoit Treluyer and Marcel Fassler, which was a further 29s behind.
The leading Audi has stopped for a brake change on two occasions, while the #2 R8 and the BMW have so far only stopped for brakes once.
The third of the WRT Audis, shared by Christopher Mies, Frank Stippler and James Nash, was a lap down in fourth position, one lap up on the Sainteloc R8 of Stephane Ortelli, Edward Sandstrom and Gregory Guilvert.
The best Mercedes-Benz SLS AMG, the additional HTP Motorsport car driven by Maximilian Buhk, Maximilian Gotz and Jazeman Jaafar, held sixth position.
The Pro-Am category was led by the AF Corse Ferrari 458 driven by Michele Rugolo, Craig Lowndes, Andrea Piccini and Steve Wyatt after the Villorba Corse entry pitted out of the lead just before 18 hours.
There has been no statement on the condition of British driver Marcus Mahy, who was airlifted to hospital after a major accident in his Kessel Racing Ferrari that resulted in the race being red-flagged just before one-third distance.
Leading positions after 18 hours:
Pos Drivers Team/Car Gap
1. Vanthoor/Winkelhock/Rast WRT Audi 382 laps
2. Luhr/Werner/Paltalla Marc VDS BMW -1 lap
3. Fassler/Lotterer/Treluyer Nova Audi -1 lap
4. Mies/Stippler/Nash WRT Audi -2 laps
5. Ortelli/Sandstrom/Guilvert Sainteloc Audi -3 laps
6. Buhk/Gotz/Jaafar HTP Mercedes -4 laps
7. Christodoulou/Buurman/Parisy Black Falcon Merc -4 laps
8. Wyatt/Rugolo/Lowndes/Piccini AF Ferrari -5 laps
9. Schneider/Primat/Verdonck HTP Mercedes -5 laps
10. Hommerson/Machiels/Bertolini/Cioci AF Ferrari -6 laps