Russell Crowe's 'Les Miserables' audition was the ''most difficult'' of his life.The actor plays Javert in the big screen adaptation of the musical but before landing the role he was subjected to a series of rigorous tryouts. A source said: ''He had to come in and sing live onstage in London in front of a huge panel, including the director, producers and various actors who had played Javert on Broadway. They totally grilled him giving him notes and rigorous critiques. He said it was the mist difficult audition of his life but that he was desperate to win the role.'' Russell's fame didn't impress the panel of producers but luckily his singing did. The insider added: ''It was like 10 Simon Cowells. They didn't hold anything back and he was really vulnerable because he's insecure about his singing. He felt like a freshman in high school auditioning for the school play. No one seemed to care that he was the Russell Crowe, Oscar winner.''