Felipe Nasr has taken the No. 31 Action Express Racing Cadillac DPi-V.R behind the wall with a gearbox problem with under five and a half hours remaining.
The Brazilian driver said he heard a loud bang while selecting fourth gear exiting Turn 6 and limped the car back to the pit lane.
The car, which he shares with Pipo Derani, Mike Conway, and Chase Elliott, had been an early front runner but was dealing with floor and exhaust damage for the last ten hours.
The crew is attempting to repair the car with the hopes of returning to the track.
Alexander Rossi leads the race overall in the No. 10 Wayne Taylor Racing Acura ARX-05 but was under threat from the charging Kevin Magnussen in the Chip Ganassi Racing Cadillac before a yellow flag was displayed due to debris on the track.
Matthieu Vaxivierre leads in LMP2 for Tower Motorsport, while Nick Tandy is in front of a Corvette Racing 1-2 in GT Le Mans.
Riley Motorsports’ Scott Andrews holds a four lap lead over his closest pursuer in the LMP3 class, while Nicklas Nielsen is out in front of GT Daytona for AF Corse.