Idris Elba has said that he was stunned when he landed the role of Nelson Mandela in Mandela: The Long Walk to Freedom.

The 40-year-old actor admitted that he has spent hours researching the role of the legendary anti-apartheid activist and former President of South Africa.

Speaking to GQ magazine, Elba said: ''I was blown away. Me? Nelson? No way, no way! You want a real man, not a man from Hackney.

''I was deeply important for me to understand where Mandela came from. Because we know where he was going, and that's a famous story, but who was he?

''Where did he come from? What was his upbringing? And that's what we focus on in the film.''

The Thor star further explained that he isn't concerned about what critics think of him playing Mandela, as the man himself has given him the thumbs up.

While watching a clip of Elba portraying him, Mandela said: ''Is that me?''

Idris further pitched in: ''Game over. Thank you. So whether anyone else sees this film, I don't care. If I can convince the man himself that's enough for me. ''