A competition Giulia was introduced at the 1963 FISA Monza Cup. Named for its tubular space-frame chassis and striking aluminium Zagato coachwork, the Giulia TZ (Tubolare Zagato) took the first four places in its class. In 1964, the TZ was FIA homologated (100 units were needed for homologation to the Gran Turismo category) and immediately began logging its impressive string of race wins in Europe and North America. It is believed that, in the end, 100 or so examples were built between 1963 and 1967.
A purpose-built competition GT, the TZ (often called the TZ-1 to distinguish it from the later TZ-2) development was guided by Autodelta, led by ex-Ferrari engineer Carlo Chiti. The TZ shared the same basic 1,570–cubic centimetre engine with the Sprint Speciale and Spider Veloce (later, with the addition of a twin-plug cylinder head). The transmission had heavy-duty, close-ratio gears and a very quick short-throw lever. Reduced bonnet height was achieved by tilting the engine in the frame. The front suspension was a similar design to the standard Giulia, while the rear was an elaborate independent competition type to reduce unsprung weight.