Felipe Nasr topped the timing sheets in the #31 Whelen Engineering Cadillac DPi-V.R. for the opening practice session for this weekend's IMSA Motul Petit Le Mans.
The Brazilian posted a best time of 1:09.093 to edge the two Acura Team Penske cars by six and eight-tenths respectively, with Ricky Taylor leading the #6 sister car.
Nasr opted to set just nine laps as tyre saving came into play for the championship contender. He and team-mate Pipo Derani hold an outside chance of taking the title as they sit 12 points adrift of Dane Cameron and Juan Pablo Montoya.
Colin Braun was fourth for CORE Autosport Nissan, almost a second adrift of Nasr's time as he failed to dip into the 1:09s with a time of 1:10.022.
Mazda Team Joest's duo came in fifth and sixth with Timo Bernhardt leading the way with a time of 1:10.169. A trio of Cadillac's completed the DPi runners with the sole Juncos Racing car in tenth.
GTLM was a closer affair, with the top five cars covered by just over two-tenths, with the #66 Chip Ganassi Racing Ford GT driven by Richard Westbrook topping the times with a 1:16.810.
James Calado was second in the #62 Risi Competizione Ferrari 488 GTE, just under a tenth back, followed by the second Ford GT of Dirk Mueller.
Leading the GTD field was the #96 Turner Motorsport BMW M6 GT3 of Bill Auberlen, heading Jack Hawksworth by 0.290s in the #14 Lexus.
The session saw two red flags; the first coming when the #48 Paul Miller Racing Huracan crashed, resulting in suspension damage and an 11-minute stoppage.
The #14 AIM Vasser Sullivan Lexus came to a stop with a puncture, causing a stoppage as it was recovered.
