Morgan Spurlock, the creator of documentary Supersize Me and director of One Direction's first feature film This Is Us has told ITV London that he believes the film is set to be a "doc-buster".
Spurlock said the band's followers were on as "epic scale" and was "beyond his comprehension".
One Direction have told ITV News that although the comparisons with The Beatles are "flattering", it was not something they agreed with.
Directioners descended into London's Leicester Square in their thousands this evening, for the world premiere of One Direction: This is Us.
One Direction's first movie premieres today ... but what does it have in store for the boyband's fans?