Ferzetti began to work on American projects. He starred as Lot in John Huston's biblical epic, ' (1966), based on the Book of Genesis. He also made his television debut with his appearance in two episodes of the American spy series, "I Spy". Ferzetti starred in "A ciascuno il suo" ("We Still Kill the Old Way", 1967) under director Elio Petri, and the TV series '. Ferzetti featured in a total of eight films released in 1968, including Marcello Fondato's "I protagonisti", Salvatore Samperi's "Grazie zia", José María Forqué's "Un diablo bajo la almohada", Roberto Faenza's "Escalation", Alberto De Martino's "Roma come Chicago", and Sergio Leone's western epic, "Once Upon a Time in the West", in which he played Morton, the railroad baron, opposite acclaimed actors Henry Fonda and Charles Bronson.