The 77-year-old – who played the main protagonist Michael Corleone in the Godfather – was joined by co-stars Robert De Niro and Diane Keaton as he made the surprising admission that he thought the film would fail during a Q&A at the 45th-anniversary screening at the Tribeca Film Festival in New York yesterday (April 30).
Speaking at Radio City Music Hall, Pacino admitted that it was the wedding scene with Diane Keaton which caused him concern after it was filmed in artificial light, due to production being behind schedule.
It even led him and some of those involved with the 1972 feature to drown their sorrows with alcohol.
He explained: 'Diane and I in that wedding thing… I mean we got so loaded after that wedding scene. A lot of chaos going on there. We got back, and we started drinking and we were just talking about 'where do we go from here? We're done. It's the worst film ever made'."
But the Francis Ford Coppola directed film was a hit.
Not only did it scoop three Academy Awards including best picture, it was recognised with nods from the National Society of Film Critics, National Board of Review and the David di Donatello Special Award.
Additionally, Pacino – who later went on to win a best actor Oscar for his role in Scent Of A Woman – ended up reprising his role a two more times, resulting in one of the most acclaimed film trilogies of all-time.
The second instalment, Part II, became the first sequel to win a best picture Oscar.
Coppola's daughter Sofia, who had two uncredited roles in the first two films and played Michael's daughter in the third, was also in attendance at the screening with husband Thomas Mars.
Other stars spotted at the event included Katie Holmes, Whoopi Goldberg, Peter Fonda and wife Margaret DeVogelaere.