Channing Tatum's burnt penis improved 'The Eagle'.

The actor suffered the agonising injury after a set assistant poured water down his wet suit to ward off hypothermia during filming but failed to check the temperature, and director Kevin Macdonald believes his discomfort made the star's final scenes more believable.

Kevin told Total Film magazine: "In some ways it did me a favour because what I was trying to do in that section was break him down.

"But Channing's such a bulk and so strong and capable that it's very hard to make him feel like he's reached the end.

"He could hardly walk but it was good because it meant that when he was fighting in the final battle he was in pain and couldn't do it very well."

Channing described the injury as "unbelievable brutal" but is grateful he wasn't left with permanent damage.

He said: "There are no words . It was unbelievably brutal.

"There's no scars or anything. I remember the medic saying, 'I know it's no consolation now, but it's a good thing it hurts because it means there's no nerve damage."