In 1967, he was signed by Scuderia Ferrari, initially competing in sports car racing. That year, Ferrari lost several drivers, including team leader Lorenzo Bandini who died from injuries sustained at that year's Monaco Grand Prix and Williams' sports car co-driver, Günter Klass, killed during practice at the Mugello Circuit in July. Later that year, Williams was offered a drive in F1, but after only one Grand Prix he was dropped by Ferrari and a subsequent F1 project with Abarth did not come to fruition. However, he did compete in some Formula Two events in 1968 winning the Rhine Cup race in a car entered by Sir Frank Williams, before driving the works Serenissima. In 1969 he helped develop the De Tomaso F1 car for Frank Williams as well as continuing to compete in F2.