GTLM championship leaders Oliver Gavin and Tommy Milner were the fastest in class with the #4 Corvette C7.R, they set the quickest time in the session, 1:15.669.
Their team-mates Jan Magnussen and Antonio Garcia were second fastest at the wheel of the sister #3 Corvette C7.R, just 0.022 behind the leading Corvette.
The top-three in GTLM was completed by the BMW Team RLL run #25 BMW M6 GTLM driven by Bill Auberlen and Dirk Werner.
Ford Chip Ganassi Racing #67 Ford GT was fourth. Porsche North America #911 Porsche 911 RSR was fifth. BMW Team RLL #100 BMW M6 GTLM was sixth. Ford Chip Ganassi Racing #66 Ford GT was seventh. Porsche North America #912 Porsche 911 RSR was eigth. Risi Competizione #62 Ferrari 488 GTE was ninth.
The second practice session is coming up next.