Porsche's return to the 24 Hours of Le Mans after a 16-year absence in the top category has made the race less predictable.
Only Toyota could realistically challenge Audi's dominance in the past two years. But Porsche's performances this year suggest Le Mans will be even more competitive.
Toyota will start from first and third on the grid on Saturday after Kazuki Nakajima became the first Japanese driver to take pole position. Toyota will be under pressure from Porsche, whose cars will start from second and fourth. Audi showed a lack of pace in qualifying and its three cars will start from fifth, sixth and seventh.
However, speed is no guarantee of victory. Reliability matters just as much in a competition won by the team that completes the most laps in 24 hours, with up to three drivers alternating. The 82nd race starts on Saturday at 1300 GMT.
Here are five things to know about the 24 Hours of Le Mans this weekend:
NO DUVAL: A year after Danish driver Allan Simonsen crashed into a barrier 10 minutes into the race and died in hospital, 2013 champion Loic Duval of France was fortunate to escape with just grazes when he crashed in practice on Wednesday. Duval spent one night in hospital as a precaution, but a doctor's report prompted Le Mans officials to disallow him from competing this weekend. He was replaced by Spanish driver Marc Gene, who won Le Mans with Peugeot in 2009.
PORSCHE'S EXPECTATIONS: Porsche is the most successful manufacturer at Le Mans with 16 titles, followed by Audi with 12. It showed its potential by finishing third at Silverstone, Britain, and fourth at Spa-Francorchamps, Belgium, in the world endurance championship this year. Reliability will be the main concern for Porsche, which is relying on the experience of Australian driver Mark Webber. "For the return of Porsche at Le Mans, finishing the race would be OK," Webber said. "For me, Audi remains the team to beat." Webber participated in Le Mans in 1998 and 1999 before winning nine Formula One races.