Porsche is back at the sharp end of the Le Mans 24 Hours grid, and Toyota returns with its most concerted assault yet since rejoining the prototype ranks in 2012. They are both attempting to end a run of Le Mans victories for Audi - a marque that's so far struggled in this year's World Endurance Championship - that stretches back to 2010.
That's why Le Mans this year is the most eagerly anticipated in years.
New rules for the LMP1 category, based on energy consumption, were crucial in tempting Porsche back for the first time since 1998, but they are also going to play a central role in this year's French showpiece. The playing field in the diesel versus petrol battle has finally been levelled, though the debate over the regulations isn't entirely over.