Denzel Washington has revealed that he always remains sober when he's filming.
The two-time Oscar winner plays alcohol-loving pilot Captain Whip Whitaker in Flight, but said that there wasn't any real booze on set. The whisky was replaced by watered-down tea.
"I don't usually drink on any movies. I can't work like that," he said.
The 58-year-old, who is up for another Oscar for his role as Whip, learnt the hard way that drinking real booze doesn't always enhance his performance.
"Years ago, right here in London, I did a movie called For Queen And Country and there was one scene where we were supposed to be drunk," he recalled.
"As young actors, we actually had some drinks and we thought we were great, but the director was like, 'You guys were awful. What's wrong with you?' So that cured me of that. Getting drunk doesn't work."
Denzel didn't do any research into alcohol or substance addiction because Whip "doesn't think he has a problem", but he did prepare for the role by doing some training in a flight simulator.
"We were allowed by Delta Airlines to use their flight simulators, which was great, and I wish I could have taken one of those home. It's what the pilots practise in and was incredibly helpful," he said.
"It gave me a sense of knowing what I'm doing. I may have not been pushing the right button, but I looked like I knew what I was doing."
:: Flight opens in cinemas on February 1.