Bill Auberlen led the way in the opening Fanatec GT World Challenge America powered by AWS practice session at Road America, in a BMW sweep of the top three positions.
Auberlen, in the No. 28 ST Racing BMW M4 GT3, reeled off a best lap time of 2:05.773 in the 60-minute session, outpacing the Pro-Am class-leading No. 29 Turner Motorsport entry of Robby Foley by 0.452 seconds.
Neil Verhagen was third quickest, just 0.005 seconds slower than Foley, in the No. 38 ST BMW.
The No. 93 Racers Edge Motorsports Acura NSX GT3 Evo22 of Zach Veach and Luca Mars was best of the rest in fourth, with Tom Sargent completing the top-five int he No. 32 GMG Racing Porsche 911 GT3 R.
Andy Lee slotted in sixth in his new Flying Lizard Motorsports BMW, ahead of the Pro class championship-leading No. 120 Wright Motorsports Porsche of Elliott Skeer and Adam Adelson.
The debuting No. 99 Random Vandals Racing BMW of Madison Snow and Kenton Koch was eighth, with the twwo DXDT Racing Chevrolet Corvevtte Z06 GT3.Rs completing the top-ten, led by the Pro-Am class entry of Bryan Sellers and newcomer Bryson Morris.
The Am class, which features two cars this weekend, meanwhile, was paced by the No. 163 AF Corse Ferrari 296 GT3 of Ozz Negri.
The session was red-flagged with 13 minutes to go after an heavy accident by Ross Chouest in the No. 50 Chouest Povoledo Racing Mercedes-AMG GT3 Evo in Turn 5.
Officials elected to end the session early as a result of significant debris on track.
Chouest climbed from the wrecked car under his own power.
The second and final practice session of the day is set for 3:15 p.m. CDT.
RESULTS: Practice 1