Hartley leads as torrential rain hits Le Mans
Porsche 919 Hybrid N.20 driven by New Zealand Brendon Hartley on June 12, 2014 in Le Mans, western France - by Jean-Francois Monier
Stephane Sarrazin in a Toyota TSO40-Hydrid N.7 was 12 seconds back after four hours of racing after the world's most celebrated endurance race began under sunny skies and with 54 cars on the starting grid.
Violent rainfall flooded the circuit and made visibility almost impossible as the race organisers sent out the safety car twice.
Defending champions Audi were badly hit by the weather which forced one of their three cars, compared to the two vehicles of Porsche and Toyota, driven by Marco Bonanomi out of the race following an accident.
The 82nd version of the legendary race, over a road circuit in western France, was sent on its way by former Formula One world champion Fernando Alonso earlier on Saturday.
The field was led from the front by the Toyota TS040 hybrid car driven by a team headed by Alexander Wurz of Germany, ahead of the Porsche 919 hybrid of Switzerland's Neel Jani.
On the second row of the grid was a second Toyota, driven by Nicolas Lapierre of Switzerland, just ahead of a Porsche which featured another former Formula One ace, Mark Webber of Australia, returning to the race for the first time in 15 years.
Webber's last appearance was marred by a famously spectacular accident on the Hunaudieres straight, when his Mercedes literally took off.