The #8 Toyota had been at the head of the field as dawn broke at the Circuit de la Sarthe, but Ryo Hirakawa started to lose time with a damaged front splitter and a slow right-rear puncture to his GR010 HYBRID contender.
This brought the #51 Ferrari 499P of Alessandro Pier Guidi into play, with the Italian closing a 11s gap with a series of rapid laps.
Pier Guidi was able to bring himself right on the tail of Hirakawa but couldn’t make a move by the time the two drivers simultaneously headed to the pits at the end of lap 207.
Toyota elected to change the front end of the #8 Toyota during the pitstop, which proved crucial in the battle for the lead as it allowed the #51 Ferrari now driven by James Calado to exit ahead.
The gap between the two cars stood at five seconds after the pitstops, and Calado was able to extend that advantage to well over 13 seconds as the Ferrari enjoyed a pace advantage over the Toyota.
During the next round of pitstops, Hirakawa took on new tyres while Calado continued on old rubber, with the gap between the two expanding to 25s as they rejoined the track.
Using fresher tyres, Hirakawa was able to bring the deficit down to 20s but Calado maintained his own to maintain Ferrari’s advantage at the head of the field.
Calado and Hirakawa handed over their cars to Antonio Giovinazzi and Sebastien Buemi respectively and, as the clock struck the 18th hour, Ferrari’s advantage had ballooned to nearly a minute, aided by deployment of a slow zone that appeared to cost the Toyota.
The #2 Cadillac consolidated third position after some quick stints from Alex Lynn and Richard Westbrook, although it continues to circulate three minutes off the lead, making the fight for the overall win a two-horse race between Ferrari and Toyota.
Scott Dixon runs a lap down in the #3 Cadillac in fourth, while Mikkel Jensen holds fifth in the #93 Peugeot.
Porsche’s challenge crumbled at the start of the 17th hour when Kevin Estre crashed the best-placed of the three 963 LMDhs while trying to lap an LMP2 car.
Running in fifth position behind the #3 Cadillac of Sebastien Bourdais, Estre made a mistake as he attempted to pass an LMP2 car and went straight off at the Porsche Curves, skating through the gravel before hitting the tyre barriers side-on.
The Frenchman was able to reverse out of the barriers and rejoin the track, but had to bring the #6 Porsche back into the garage, where it spent a whopping 43 minutes undergoing repairs to the floor and bodywork.
That made the #5 car of Michael Christensen the leading Porsche in sixth, albeit six laps down on the #51 Ferrari with six hours of racing remaining.
Both Glickenhaus cars suffered crashes in the 18th hour, with Olivier Pla going wide at the exit of Indianapolis and slamming the barriers on the inside of the corner in the #708, before Franck Mailleux had a similar - but slightly less impactful - shunt at the same corner in the sister #709 car.
Both drivers were to rejoin the race after brief trips to the garage to repair damage.
In LMP2, Inter Europol continues to hold the class lead despite the best efforts of Robert Kubica in the #41 WRT car to snatch the top spot.
Now driven by Albert Costa, the #34 ORECA remains over 30s clear of the #41 WRT car piloted by Rui Andrade, with Job van Uitert moving the #65 Panis Racing ahead of the #30 Duqueine machine of Neel Jani in the battle for the final spot of the podium.
The GTE Am saw a number of lead changes with the Kessel Racing Ferrari that had led in the hands of gentleman driver Takeshi Kimura dropping to seventh place.
Kimura was passed by the #85 Iron Dames Porsche of Rahel Frey on the Mulsanne Straight in the 17th hour, with Frey staying in the car to strengthen the lead of the all-female crew.
Second place is held by the #25 ORT by TF Aston Martin of Charlie Eastwood, who overtook the #33 Corvette of Ben Keating just before the end of the 18th hour.
Meanwhile, Mike Rockenfeller runs 29th overall in the Garage 56 Chevrolet Camaro, ahead of all GTE Am runners in the field.
