In 1925, the AIACR introduced the World Manufacturers' Championship. Alfa Romeo did not contest the first race, the Indianapolis 500, but instead headed to Spa-Francorchamps for the Belgian Grand Prix. Twelve drivers from four teams entered the race, but only seven turned up, from two teams: Alfa Romeo and Delage. By half way, four of the seven had retired, and by two-thirds way, only Ascari and his team-mate Giuseppe Campari remained. Ascari won the race by 21 minutes 58 seconds, with Campari having to drive twice around the circuit on his own to complete his race.