James McAvoy has revealed his sex scenes with
Keira Knightley for the film Atonement were a "sweaty and uncomfortable nightmare".
The 28-year-old actor felt so awkward while filming the raunchy scenes he kept apologising to Keira when the cameras stopped rolling.
James said: "It's always a nightmare filming sex scenes, isn't it? It's never easy and it's always a little bit sweaty and uncomfortable.
"When they call action, if you feel the lady's breast, it's your decision to feel the lady's breast. It's like, this is wrong. You have no parameters.
"We carried on and about 10 seconds later we just said very sheepishly, 'Sorry about that'."
The Last King of Scotland star - who Keira described as "the best kisser ever" - was pleased director Joe Wright ordered them around during the passionate scene.
He said: "What was great about Atonement was Joe Wright was very on the ball with what he wanted, so when you were doing something it was at his behest."
James has just finished shooting Wanted, in which he plays a young man who learns that his long lost father is an assassin.