Christopher Haase has the No. 29 Audi Sport Team Land Audi R8 LMS out front after three hours in the California 8 Hours at Mazda Raceway Laguna Seca.
The German team has led the bulk of the race after starting on pole, only briefly losing the lead during pit stop shuffles.
Haase has an 18.980-second lead in hand over the No. 44 Audi Sport Team Magnus machine of Markus Winkelhock, while Tom Dyer holds third in the last remaining Acura NSX GT3 for RealTime Racing.
The sister No. 93 RealTime Racing Acura was officially retired from the race with a cooling problem, having gone behind the wall in the first hour.
Robin Frijns in the No. 1 Team WRT Audi and Ben Barnicoat in the No. 9 K-PAX Racing McLaren 650S GT3 complete the top five.
Other class leaders include Jeroen Bleekemolen in the No. 54 Black Swan Racing Porsche 911 GT3 R in GT3 Pro-Am, Hadrian Morrell in the No. 193 MARC Cars Australia Marc Mazda 3 V8 in the invitational class, and Craig Lyons in the No. 3 Aston Martin GT4 for TRG.
After bringing out the only safety car of the race so far in the opening hour, the No. 99 Automatic Racing Aston Martin of Charles Espenlaub has returned to the race after making repairs and currently runs in 18th overall, eighth in the GT4 category.