Nick Tandy in the No. 19 Porsche is in full control of this race at the moment - but things can change at Le Mans without a moment's notice. Here is a recap of the 18th hour as the 83rd running of the 24 Hours of Le Mans has reached its final fourth. 

LMP1

Tandy climbed into the leading Porsche 919 Hybrid after Nico Hulkenburg brought the car into the pits for refuelling during the safety car period that was caused by the crash of the No. 96 Aston Martin of the GTE Am category. The crew of the leading No. 19 Porsche was pushed into the garage for minor repairs to the bodywork during this same stop - but no time was lost as Tandy would have been held at the exit of the pit lane to wait for the next safety car group to arrive anyway. 

The lead that Hulkenburg had placed in Tandy's hands was preserved as the car was in the same group as the second and third place cars when it came into the pits, meaning it rejoined the track in the following safety car group. 

Later in the hour, Tandy stopped for fuel and rejoined the track two and a half minutes ahead of Webber. 

Running fourth in the class is the No. 7 Audi R18 e-tron quattro after losing its engine cover in the Porsche Curves; it is currently being driven by Oliver Jarvis. 

The polesitting No. 18 Porsche 919 Hybrid is running two laps down after the off track excursions earlier in the race. 

Alex Wurz and Sebastien Buemi pilot the two Toyota LMP1 entries but have been unable to match the pace of the frontrunners throughout the first 3/4 of this day-long race. 

LMP2

Richard Bradley is behind the wheel of the dominant KCMG car that maintains its full-lap lead over Julien Canal in the G-Drive (OAK) Ligier. 

Another average hour passed for this category minus another spin for the Krohn Racing entry. 

Third place of Oliver Turvey has been taking a bit out of the gap between his Jota Sport car and the G-Drive Ligier. 

The Murphy Prototypes continues to run fourth, piloted at the moment by Mark Patterson. The second G-Drive entry of Pipo Derani and OAK Racing's Honda-powered Ligier entry, driven by Christopher Cumming, are fifth and sixth in the class. 

GTE Pro & Am

The No. 51 AF Corse Ferrari now has a seven-second lead over Oliver Gavin in the No. 64 Corvette C7-R. Both Vilander and Gavin pitted during the safety car period in the earliest minutes of this 18th hour as Gavin was leading at the end of the 17th. Vilander, though, brought the Ferrari in a lap before Gavin, gaining a spot futher ahead in their safety car pack. At this, he set out to build a lead. 

Third place in GTE Pro is Jorg Bermeister in the best of the Porsche GTE cars - although the car is two-minutes behind. 

The No. 98 Aston Martin Vantage V8 is continuing strongly towards a very probable GTE Am win; Paul Dalla Lana is three minutes ahead of Victory Shaitar in the SMP Racing Ferrari. 

Follow @VAVELSportsCar on Twitter for live tweeting during the final quarter of this race. 

Aaron Durant is the editor of the VAVEL USA Racing section. Follow him on Twitter at @DoubleA291.