Al Pacino, Martin Scorsese and Robert De Niro attend "The Irishman" International Premiere and Closing Gala during the 63rd BFI London Film Festival

Even after a movie career spanning half a century, legendary Hollywood actor Al Pacino says he still suffers from imposter syndrome.

"Sometimes I feel I know nothing about acting," he said in a recent interview with a panel of journalists, featured in U.K. newspaper The Guardian, but added these fears disappeared once he began to prepare for a new role.