Mercedes led the Spa 24 Hours at three-quarter distance with the Auto Sport Promotion entry shared by Raffaele Marciello, Edoardo Mortara and Michael Meadows.
The Mercedes-AMG GT3 with Marciello at the wheel held an advantage of just under 20 seconds over the chasing WRT Audi R8 LMS of Rene Rast as the blue-riband Endurance Cup round of the Blancpain GT Series hit the 18-hour mark.
The car moved firmly into contention for the victory in the hours after half distance, despite two clashes with other front-running cars.
Marciello tagged Marco Cioci in the AF Corse-run Kaspersky Ferrari, which had led much of the first half of the race, as he made a lunge down the inside at the La Source hairpin in hour 14.
The Italian subsequently came together with Rast as they battled for the lead straight after a safety-car period early in the 17th hour.
Marciello spun after contact was made with the Audi in the right-hander at Les Combes, but the drivethrough penalty handed to Rast for causing a collision restored the lead in the favour of the Mercedes.
The French Sainteloc team’s factory Audi ran third with Christopher Haase, who had Andy Soucek on his tail in the best of the M-Sport Bentley Continental GT3s.
The Team 75 Bernhard Porsche held fifth after coming back from an early three-minute stop-go penalty for a pitstop infringement to get back on the lead lap.
Defending Spa champion team Rowe Racing held sixth place with the M6 GT3 shared by Bruno Spengler, Nicky Catsburg, and Tom Blomqvist.
The AF Corse-run Kaspersky Ferrari and the full-factory Grasser Lamborghini that had run at or near the top of the leaderboard for the first half of the race both retired in the barriers.
Cioci went off at Eau Rouge straight after the contact with Marciello at La Source.
The collision clearly damaged the steering and Cioci, who shared the car with Giancarlo Fisichella and James Calado, was unable to prevent the car from spearing into the tyres as he tried to negotiate the corner.
Engelhart nosed into the barriers at Fagnes in the factory Huracan GT3 he shared with Mirko Bortolotti and Andrea Caldarelli with what appeared to be some kind of technical problem.
Pro Am class honours were led by the Black Falcon-run Mercedes lshared by Maximilian Gotz, Miguel Toril, Marvin Kirchhofer and Oliver Morley.