Graham Rahal in the #7 Acura Team Penske car took the lead after Mustang Sampling Racing made a regular pit stop after four hours of action.
The #7 car was outside of the top five at the beginning of the fourth hour, but fine driving from Rahal elevated his team into the top three with the #5 Mustang Sampling Racing car and Scott Sharp in the #2 Tequila Patron ESM car.
18-year-old Stuart Middleton was running high up the grid in the #31 Whelan Engineering Racing car, but was given a drive-through penalty for an incident with Simon Pagenaud and Team Penske’s #6 car that saw Pagenaud spin at the international horseshoe.
Tequila Patron ESM’s #22 car suffered a right rear puncture with Pipo Derani behind the wheel, which damaged the Nissan as Derani made his way back to the pits.
After suffering multiple issues on both of its cars earlier in the race, Mazda Team Joest was struck with even more bad luck as the #77 car had a left rear puncture.
In the GTLM class Dirk Mueller and the #66 Ford Chip Ganassi Racing team kept its lead over the #911 Porsche GT Team by just over ten seconds, with Chip Ganassi’s #67 car running in third in the class.
Luca Stolz in the #33 Mercedes-AMG Team Riley car held the lead in the GTD class, although the #29 Montaplast by Land Motorsport Audi with Christopher Mies behind the wheel was able to cut down the gap.
The two cars were separated by just over six seconds three hours into the race, but an hour later Mies was around one second away, with the battle starting to brew again on track.