Fangio joined Ferrari after Mercedes-Benz, with whom he had won the 1954 and 1955 titles, withdrew from the sport. Ferrari acquired the folded Lancia team's D50 cars and put together a strong team containing Fangio, Eugenio Castellotti, Luigi Musso and Peter Collins. Fangio won the opening race after commandeering Musso's car after his own car had broken down. Collins and Fangio's teammate at Mercedes, Stirling Moss – now driving for Maserati provided the biggest challenge to his title defence, each winning two races. In an open season, the British Connaughts, Vanwalls and BRMs also showed some signs of promise.