Change Racing duo Richard Antinucci and Corey Lewis extended their Lamborghini Super Trofeo North America points lead following a pair of wins at Watkins Glen.
The wins were Antinucci's 13th and 14th in the one-make category, cementing his status as its most successful driver.
Antinucci made a strong getaway as the start of Saturday's opening race as fellow front-row starter and former IndyCar driver Conor Daly dropped to fifth after being forced over the kerbs at Turn 1.
That allowed Andrea Amici up into second place in his Prestige Performance/Wayne Taylor Racing Huracan EVO with Patrick Liddy running third.
Amici hounded Antinucci for much of the opening stint before the mandatory pitstops, as the pair broke clear of Paolo Ruberti (Dream Racing Motorsport), who had passed Liddy.
Lewis then took over from Antinucci in the #29 Huracan and edged out to a 4.226 second lead over Sandy Mitchell - who had swapped with Amici - in the #1 car.
Mitchell had been closing the gap to Antinucci at the beginning of his stint before a full course yellow was brought out after D Bryce Miller spun out at the Esses following a left rear puncture.
A poor restart for Mitchell allowed Ruberti's team-mate Cedric Sbirrazzuoli to take second place and that helped Lewis open up a three-second advantage, which he held until the flag.
Sbirrazzuoli withstood several attacks from Mitchell to maintain second, but he also fell victim to a puncture on the final lap, handing back the position to Mitchell.
Teenager Steven Aghakhani took a well-deserved Am class victory on his series debut in the US RaceTronics machine, while ex-CART and IndyCar star Bruno Junqueira claimed Pro-Am honours with sixth overall.
Sbirrazzuoli started race two from pole and led Mitchell at the start, as Lewis dropped to third place.
Further back, 2003 CART champion Paul Tracy - another driver making his debut in the championship this weekend - collected Aghakhani's Huracan at the Boot, with the pair having to take to the gravel.
Am class runner McKay Snow then brought out the full course yellow by crashing at the exit of the Bus Stop chicane just before the pit window opened.
The solo Change Racing entry took too much of the exit kerb and made heavy contact with the outside tyre barriers.
Mitchell and Lewis therefore did just one lap of green running before making their stops, with Sbirrazzuoli doing the same one lap later.
Antinucci took over from Lewis and shuffled to the front, where he remained unchallenged for the rest of the race.
Ruberti emerged back out in front of Amici, and there were then joined in a big tussle for second place by Daly.
The order remained unchanged until the flag, with Ruberti coming home behind Antinucci by 3.240s.
Jake Eidson and Damon Ockey claimed the Pro-Am victory in race two after taking second place in Saturday's opening encounter - despite serving a drivethrough penalty for a jump-start.
The US RaceTronics pairing beat Ryan Hardwick and Supercross sensation Chad Reed, with the Junqueira/Bradley Baker Huracan finishing third.
Aghakhani recovered to take the Am class victory in race two, while Mel Johnson took an easy Lamborghini Cup win.