The 2013 Audi R18 led the Sebring 12 Hours at the halfway mark in the hands of Tom Kristensen.
The Dane, who shares the new R18 e-tron quattro with Allan McNish and Lucas di Grassi, held a 8.1-second lead over the 2012 version of the car driven by Benoit Treluyer shortly after the fourth safety-car period of the race had ended.
Both Audis had spells in the lead over the course of the first six hours of the opening round of the American Le Mans Series, but Kristensen moved to the head of the leaderboard during the safety car in the sixth hour.
Treluyer led by 22sec prior to the safety car before stopping for fuel, tires and a change of nose, whereas Kristensen stayed out.
McNish had earlier been penalized 60sec for avoidable contact with a LMPC class entry, although the subsequent safety cars allowed the No. 2 Audi to make up the lost time.
Third place and the best of the privateer LMP1s was the lead Rebellion Racing Lola-Toyota B12/60 driven by Nicolas Prost, who held the narrowest of margins ahead of Klaus Graf in the Muscle Milk Pickett Racing HPD ARX-03c.
The HPD, which Lucas Luhr and Romain Dumas are sharing with Graf, fell more than a lap behind the lead Rebellion Lola when Luhr lost a wheel exiting the pits.
LMP2 was led by the two Level 5 Motorsports HPD ARX-03bs, Marino Franchitti heading Scott Tucker, after erstwhile leader David Brabham in the Extreme Speed Motorsports HPD ground to a halt with gearbox failure, triggering the safety car period.
The Risi Competizione squad turned Olivier Beretta around in double-quick time under the yellows to propel its Ferrari 458 Italia into the lead in the GT class. The Monaco-based driver held a seven-second lead over Nick Tandy in the Walker Racing-run Falken Tires Porsche 911 GT3-RSR, while Chrysler's SRT Viper GTS-R ran fifth after leading prior to the safety car.