Theron was reportedly 14 kilograms (30 pounds) overweight after playing serial killer AILEEN WUORNOS in MONSTER and had no martial arts experience.
But she completed three years worth of training in just four months, thanks to her expert coach NEIL RODIL.
He says, "There is a scene in the trailer where she flips over, wraps her legs around someone's neck and snaps it.
"It's an extremely advanced and dangerous move - but she can do it.
"She went from knowing nothing to being an extremely good martial artist who knows some pretty deadly moves."