Phoenix's dream of rap career was a joke -- director

Joaquin Phoenix turned from a clean-cut actor into a bearded, druggy rap wannabe two years ago -- but it seems it was all in the name of art.

His brother-in-law Casey Affleck, who made a documentary about Phoenix's transition from acclaimed actor to shambolic hip-hop star, has admitted that it was an act.

"It's a terrific performance, it's the performance of his career," Affleck told the New York Times. Affleck said Phoenix put his professional life on the line to star in the documentary, I'm Still Here, which captivated viewers at the Venice International Film Festival this month.

At the event, Phoenix swore it was a genuine documentary despite clear indications on the screen that it was a "mockumentary" poking fun at a narrow-minded public.

The buzz about the documentary began when a bearded Phoenix appeared on David Letterman's chat show in February last year, confused and mumbling.

In the movie Phoenix is at times funny and coherent and at others childish, aggressive and paranoid as he struggles to live with his decision in 2008, which the media greeted with disbelief, to give up acting and take up hip-hop.

The film includes footage of him apparently taking drugs, surfing the internet for call girls, hosting prostitutes, diving off a stage to attack a heckler and vomiting. It also features rap impresario Sean Combs, who finally agrees to listen to a demo of his hip-hop music.