Oliver Jarvis put the No. 8 Audi R18 on top in the first Free Practice session for the Six Hours of Circuit of The Americas on Thursday.
A time of 1:48.453 in the final couple of minutes was enough for Audi Sport Team Joest to beat rivals Porsche in a session-long back-and-forth between the two German marques.
Neel Jani was just 0.047 seconds behind in his No. 2 Porsche 919 Hybrid. The No. 7 Audi and No. 1 Porsche made up the top four, with the two Toyota TS050 Hybrids behind.
G-Drive Racing was quickest among the LMP2 runners, as the No. 26 Oreca 05 Nissan set a 1:57.000.
The remaining positions in the top four were all Orecas, as Manor was third, with the two Alpine-badged cars in second and fourth.
AF Corse missed out on the GTE-Pro lead to Ford Chip Ganassi Racing. The No. 66 Ford GT topped the class with a 2:05.457, ahead of the Nos. 51 and 71 Ferrari 488 GTEs.
The fastest GTE-Am team was Larbre Competition, setting a time two seconds slower than the GTE-Pro pace-setters.
The No. 50 Corvette C7.R has an adjusted lineup this weekend, as Lars Viljoen replaces Yutaka Yamagashi.
The two Porsche 911 RSRs of Abu Dhabi Proton Racing and Gulf Racing complete the top three in class.
A full course yellow was called during the session to retrieve Darren Turner’s No. 97 Aston Martin V8 Vantage GTE, which went off track and scattered gravel onto the circuit.
Several cars were warned about track limits during the session, especially at the penultimate corner, turn 19.
Free Practice 2 gets underway at 8 p.m. local time.
RESULTS: Free Practice 1