After racing in Italian Formula 3 and Formula 2 with mixed results, Leoni moved into Formula One with a hired Surtees TS19 at the 1977 Italian Grand Prix, but failed to qualify.
Logo de competir na Fórmula 3 e Fórmula 2 con resultados mixtos, Leoni debutou na Fórmula Un cun Surtees TS19 no Gran Premio de Italia de 1977, pero non conseguiu cualificar.