Joaquin Phoenix developed an alcohol dependency while filming his role as Johnny Cash in the new movie biopic Walk The Line.
Country singer Cash, who was a renowned drinker, prompted actor Phoenix into increasing his alcohol intake for a better portrayal of the character.
Gladiator star Phoenix, 30, realised his problem was getting out of control and in April checked himself into a rehab clinic when filming was over.
He tells London magazine Time Out: "It was then that I became aware of my drinking. I wasn't an everyday drinker but didn't have anything else to do, anything to hold me down.
"I was leaning on alcohol to make me feel ok. That's what it really was."