Robbie Williams is reportedly worried about his biopic after struggling to find an actor to play his younger self.

The 'Let Me Entertain You' hitmaker and director Michael Gracey recently held secret auditions to cast the lead in 'Better Man' but were stunned when they were unable to find a young actor with the confidence to pull off the role, leaving the former Take That singer concerned the project will end up indefinitely delayed.

A source told the Sunday Mirror newspaper: “Michael and Robbie held top-secret auditions to find a star to play the young Robbie recently.

“They didn’t meet anyone they were confident could pull it off.

“Robbie is stunned at how difficult the project has been to get made. And now he’s starting to worry it’s never going to make it to the big screen and he’ll look foolish for hyping it up.

“The London-based studio, Rocket Science, is handling international sales on the project and is hoping for a big hit.

“Robbie has fans all over the world and his story is not short of drama. But if they can’t find a star charismatic enough to play him, the whole house of cards is going to come falling down and it’ll end up in development hell.”

The 'Rock DJ' hitmaker is due to have an upcoming Australian concert recorded for the film, with fans attending the show at Melbourne's Rod Laver Arena asked to wear 90s clothing as Robbie will be digitally altered to look as he did back then.

The movie will tell the story of Robbie's rise to fame and the experiences that shaped him as he became a huge star on the back of hits with Take That and a successful solo career.

Michael has penned the script for the flick alongside Oliver Cole and Simon Gleeson and revealed that the movie came about after hours of conversations with the 'Candy' singer and through his determination to tell the story of an "everyman".

The filmmaker previously said: "Unlike some people who were born prodigies or musical geniuses and you follow the narrative of the world catching up to their brilliance, this isn't that story.

"Robbie is that everyman, who just dreamed big and followed those dreams and they took him to an incredible place. Because of that, his is an incredibly relatable story. He's not the best singer, or dancer, and yet, he managed to sell 80 million records worldwide."