Campbell, the 28-year-old Aussie, extracted a flying lap of 1m15.184s around the 14-turn, 2.439-mile road course to put the Porsche 963 alone at the top.
Filipe Albuquerque (Wayne Taylor Racing with Andretti Autosport) kept it close, trailing by 0.022 of a second in the #10 Acura ARX-06.
Sebastien Bourdais and Renger van der Zande came away third in Chip Ganassi Racing’s #01 Cadillac V-Series.R, with the former nailing the best lap that fell 0.216s off the Campbell’s pace-setting lap.
Mikkel Jensen provided a jumpstart to the weekend for TDS Racing, pushing his #11 ORECA LMP2 07 to a class-best lap of 1m17.231s.
Ryan Dalziel was a close second in the #18 entry to a narrow 0.055 of a second behind for Era Motorsport. The #04 Crowdstrike Racing by APR entry was also in the mix in third, with Ben Hanley 0.01 behind second and 0.056s off the top spot.
Jr III Racing’s Ligier JS P320 driving by Garett Grist and Nolan Siegel, who was crowned Indy NXT Rookie of the Year last weekend in IndyCar’s season finale in Laguna Seca, led the LMP3.
Grist handled the honors with a flying lap of 1m20.737s, which was 0.062 of a second ahead of second-in-class, Matthew Bell in the AWA Duqueine D08.
The #14 Vasser Sullivan Lexus RC F GT3 was fastest in the class (27th overall), with Jack Hawsworth setting the pace with a quick lap of 1m23.636s.
Klaus Bachler was a distant second, 0.585s behind in the Porsche 911 GT3 R (992) for Pfaff Motorsports.
Patrick Gallagher elevated Turn Motorsport’s #96 BMW M4 GT3 to best in class (and 28th overall) after brewing up a lap at 1m24.019s.
The #78 Lamborghini Huracan GT3 EVO2 was second with Loris Spinelli’s best lap falling 0.123 of a second off Gallagher’s mark.
The only red flags in the session came from competitors in the GT Daytona category. The #77 Porsche 911 GT3 R (992) for Wright Motorsports went off in Turn 4 and was left stranded in the gravel trap, which brought out the first red flag with 50 minutes remaining in the session.
A second red flag came out with just under 17 minutes left after the slow moving #94 Aston Martin Vantage GT3 for Andretti Autosport (Jarett Andretti, Gabby Chaves) caught on fire and was forced to pull off in Turn 7.