The Wire star is currently filming thriller No Good Deed in Atlanta, Georgia and he will head to South Africa just one day after production wraps to begin work on Long Walk to Freedom, which will chronicle Mandela's struggles with apartheid, his 27 years in prison and his rise to political power.
But Elba is worried his portrayal of Mandela will suffer because of his busy schedule.
He tells New York magazine, "It's one of my biggest opportunities, and I can't think about preparation or where my head is at. I just get this sinking feeling as soon as I open my mouth. I wish I wasn't working directly up to it."
Elba is the latest actor to tackle the role of Mandela - Terrence Howard and Morgan Freeman have both played the humanitarian hero in Winnie and Invictus, respectively.
Naomie Harris is slated to star opposite Elba as his onscreen wife, Winnie Mandela.