Mike Conway put the Action Express Cadillac on top in final practice for the Daytona 24 Hours, edging out Williams Formula 1 driver Lance Stroll.
Toyota LMP1 driver Conway ousted Stroll from the top of the times just over 20 minutes into the one-hour session on Friday with a best time of 1m36.865s aboard the #31 Cadillac DPi-V.R.
That demoted Stroll in the #38 Jackie Chan DC Racing Oreca LMP2 to second place, 0.181 seconds behind Conway and a tenth ahead of Tristan Vautier in the #90 Spirit of Daytona Cadillac.
DTM champion Rene Rast put the best of the Joest-run Mazda DPis, the #77 car, in fourth place, while the sister #55 machine missed the session due to an engine change.
Filipe Albuqerque made it three Cadillacs in the top five in the second Action Express machine.
The two cars that will start from the front row on Saturday were seventh and eighth-fastest, with Graham Rahal in the best of the Team Penske Acura ARX-05s leading Jordan Taylor's polesitting Wayne Taylor Racing Cadillac.
Fernando Alonso was 16th-fastest in the #23 United Autosports Ligier JSP217, 1.930s off the pace and two places behind the sister #32 car that suffered a puncture while Bruno Senna was at the wheel.
In GT Le Mans, Joey Hand led the way in the #66 Ford GT with a best time of 1m44.602s, 0.057s up on Gianmaria Bruni in the best of the Porsches.
The class pole-sitting #3 Corvette was seventh-fastest ahead of the two all-new BMW M8 GTEs.
Porsche driver Matteo Cairoli was fastest in the GT Daytona class in the #59 Manthey 911 GT3 R.