Thandie Newton was "terrified" of playing Condoleezza Rice. The 'Run, Fatboy Run' star had no prior knowledge of the US Secretary of State before she agreed to portray her in 'W' - the forthcoming biopic of US president George W. Bush - and says this made her apprehensive about taking on the daunting part. She said: "When director Oliver Stone first approached me, I knew nothing about Condi. Obviously I'd seen her on the news but I didn't even know how many Zs she had in her name. "I felt sheer terror about whether I could actually unlock the character. She's right there on our TV screens. Everyone knows how she moves, how she speaks. It's the most terrifying role I've had and that fear made me feel very alive." Almost immediately after completing work on 'W', the British star started filming '2012', which is about an academic battling to prevent the apocalypse, and admits she found the change a "headf**k". She added to Britain's Independent newspaper: "It didn't help that work started on '2012' so soon after finishing 'W'. I'd shot my last scene as Condi, then days later I'm stood in a different Oval Office playing the president's daughter. "That was such a headf**k. You really need to lay low before you plant the seeds of a new character."