Beyonce Knowles got psyched up to fight Ali Larter's crazed stalker character in new movie OBSESSED by pretending someone was threatening her sister Solange's young son.
Larter plays a crazed office temp who tries to seduce Knowles' character's husband in the suspense thriller.
And the pair shock movie audiences by violently grappling, punching and headbutting each other.
Knowles reveals she mustered up the rage to battle Larter by picturing an imaginary attacker tackling her four-year-old nephew Daniel.
She tells the New York Daily News, "To prepare, I tried to tap into things that are available to a lot of people. I thought about my sister and what it would be like if someone were threatening her child. I used my life experiences and my nephew to get my mind right.