CGR driver Sebastien Bourdais propelled the #01 Cadillac V-LMDh to first position shortly after the end of the 15th hour after passing the Porsche of Nick Tandy, who had been struggling on old tires and subsequently headed to the pitlane for fresh rubber.
This initially established a Cadillac 1-2 at the head of the field, with Alex Lynn trailing Bourdais in the #02 car, but MSR moved back up to second when Tom Blomqvist passed Lynn’s teammate Richard Westbrook in the 16th hour.
The gap between Bourdais and Blomqvist initially remained stable at around 28 seconds before the reigning champion gradually started eating into the lead of the Frenchman, bringing the deficit down to 10 seconds when he headed to the pits with seven hours to go to hand over the #60 Acura ARX-06 to Colin Braun.
By the time Braun returned to the track the gap between the two cars had stretched back to 32s, with Renger van der Zande having pulled out a big advantage on fresh tires after taking over the #01 Caddy from Bourdais.
Braun wasn’t able to respond to van der Zande’s pace on old tires, but MSR remains CGR’s main competitor for victory despite previously dropping off the lead lap twice at night due to two unscheduled pitstops for an oil leak.
Third place is currently held by Earl Bamber in the #02 CGR Cadillac, more than a minute down on the sister entry that is now driven by Scott Dixon.
The #24 BMW runs fourth in the hands of Marco Wittmann with a consistent and a trouble-free run, albeit two laps off the lead.
Ricky Taylor is also circulating two laps down in the #10 Wayne Taylor Racing Acura, still recovering from the oil leak issue that has also compromised the race of the MSR team.
Porsche’s hopes of winning the Rolex 24 on its return took a severe blow at the start of the 16th hour when Nick Tandy suffered a spin while trying to navigate traffic, damaging both the front and rear-end of his car.
The repairs dropped the #6 crew three laps down and, with the #7 car already out of contention with mechanical troubles, the German manufacturer is effectively out of the fight for win with six hours remaining in the race.
The Action Express Racing team is also no longer in the battle after the gearbox problem that hit the squad just before Hour 15 forced Pipo Derani to bring the #31 Cadillac behind the wall for repairs.
Having lost 17 laps, the AXR Caddy currently sits seventh in the GTP class, just ahead of the #7 Porsche and the #25 BMW that were hit by their own issues during the night.
The LMP2 class featured a straight battle between the #04 Crowdstrike by APR Oreca and the similar #35 PR1/Mathiasen machine, with Job van Uitert putting the latter in front in the 18th hour of the race.
Sean Creech Motorsport returned to the lead in LMP3 class, with Joao Barbosa heading the field in the #33 Ligier.
Meanwhile, the WeatherTech team remains in front in GTD Pro, with Jules Gounon holding an eight-second advantage in the team’s #79 Mercedes-AMG GT3.
Corvette’s strong recovery continued with impressive stints from factory drivers Tommy Milner and Antonio Garcia helping the squad move back up to second before sunrise, ahead of the #14 Vasser Sullivan Lexus currently driven by Mike Conway.
There were multiple changes for the lead in GTD, with Daniel Morad grabbing the top spot in the #57 Winward Mercedes from Marco Sorensen in the #27 Heart of Racing Aston Martin Vantage GT3.
Third place is currently held by Andy Lally in the Magnus Racing Aston that had previously been hit with a 60-second penalty for exiting the pitlane while the red light was on.
