Bradley Cooper, star of 'The Hangover', has cited Robert De Niro as the actor who inspired him to pursue a career in acting.

In an interview with The Boston Herald, Cooper praised his 'Limitless' co-star De Niro as his inspiration and muse.

“'Raging Bull’ was the first thing that I saw him in, but I was so disconnected from it that all I could get was the emotional experience and not really what De Niro was doing,” said Cooper.

“But ‘The Mission’, ‘Awakenings’ and then of course ‘Deer Hunter’ and ‘Jacknife’, so many movies. ‘Falling in Love’ and when he played Capone in ‘The Untouchables’. I mean, I’ve seen everything.”

In the interview, Cooper also scotched rumours that Hollywood bad boy, Charlie Sheen, will appear in the sequel to the $277m-grossing 'The Hangover'.

“Well, unless they have a time machine and we can go back to Bangkok - my understanding is that we already filmed that movie. So it’s an interesting rumour to start spreading but you’d have to be a part of the Starship Enterprise, I think, to make that happen,” said Cooper.