After a near-six hour stretch of green flag running was brought to an end by a shunt for the High Class Racing LMP2 car of Anders Fjordbach in hour 21, the two Chip Ganassi Racing Cadillac V-LMDhs and the MSR Acura ARX-05 were bunched together by the ninth full-course caution of the race.
Prior to that, Scott Dixon aboard the #01 Cadillac had been some 50 seconds clear of Simon Pagenaud in the Acura, which was still losing time in the pitstops having to top up its oil following the car's earlier dramas.
The #02 Cadillac of Alex Lynn was clinging on to the lead lap, but the yellow bunched the leading three cars together for the restart.
Pagenaud immediately went on the attack against countryman Bourdais, the pair going side-by-side into Turn 1 before the Acura nosed in front exiting the International Horseshoe.
Richard Westbrook, who took over from Lynn during stops under yellow, almost cleared Bourdais but couldn't quite get the move done and settled into third place as his team-mate pursued Pagenaud.
The yellow allowed the delayed #6 Porsche 963 driven by Nick Tandy to get back on terms with the #10 Wayne Taylor Racing Acura in the battle for fourth, with the Briton making the move on Louis Deletraz. Both cars however were circulating two laps off the lead.
BMW's top runner, the #24 M Hybrid V8, was sixth and a further three laps back in the hands of Colton Herta, while Jack Aitken was a distant seventh in the AXR Cadillac following that car's earlier gearbox dramas.
Leading the LMP2 class was the #04 Crowdstrike by APR ORECA of Esteban Gutierrez, who was running less than two seconds clear of factory Ferrari driver Nicklas Nielsen in the #88 AF Corse entry.
The #52 PR1/Mathiasen Motorsports ORECA of Paul-Loup Chatin was third, having managed to get back on the lead lap after its earlier dramas, while the #35 TDS Racing machine of Giedo van der Garde slipped to fourth after opting to not stop under caution and then pitting under green.
Drama struck the long-time leading car in the LMP3 class, the #33 Sean Creech Motorsport Ligier, which lost 35 minutes in the pits due to a gearbox problem.
That left the #17 AWA Duqueine wheeled by Nico Varrone in front to the tune of 13 laps ahead of the #38 Performance Tech Motorsports Ligier.
In GT Daytona Pro, the Corvette Racing C8.R had edged out a 10-second margin over the WeatherTech Racing Mercedes-AMG GT3 prior to the full-course yellow, with the #14 Vasser Sullivan Lexus RC F GT3 the only other car on the lead lap.
All three cars were bunched together for the restart, allowing Jules Gounon in the Mercedes to pass Tommy Milner in the Corvette, with Lexus man Jack Hawksworth keeping a watching brief on the pair in third place.
The full-course yellow fell at a bad time for the GTD class-leading #27 Heart of Racing Aston Martin Vantage GT3, which now leads by only three seconds over the #57 Winward Mercedes in the hands of Roman De Angelis.
Behind Indy Dontje in the Winward car was another Aston, the Magnus Racing example of Andy Lally, the final car on the lead lap.
