That's the lesson Gina Carano's costars learned while they were filming Steven Soderbergh's Haywire. After all, Carano isn't just another new face in a Hollywood action thriller. She's a former mixed martial arts star, who is making her movie debut in Soderbergh's latest flick, which opens Friday.
"I got to be physical with some of the hottest guys in Hollywood," Carano, who tussles with Channing Tatum, Ewan McGregor and Michael Fassbender in the film, told PEOPLE at the BlackBerry-sponsored Cinema Society screening this week.
Fassbender, in particular, was the recipient of a vase to the face when the two were filming a fight scene and he accidentally KO'd Carano.
"When Fassbender slammed my head into the wall, that's the only time I went black," Carano, 29, said about the shoot, during which she also reportedly knocked out a stuntman. "And then I slammed a vase right into his face when he wasn't expecting it."
"He didn't get cut," Carano clarified, before adding, "maybe a little bit."
McGregor, for his part, said he also emerged "sore" from his scenes with Carano but called the fight scenes "good fun."
But Tatum, whom she describes as "like a bro," is one actor Carano says she wouldn't want to fight in real life. "I'd probably want to choke him out real quick," she said. "Because he's actually very athletic."
Return to MMA?Carano has officially retired from MMA but says she hasn't ruled out a return. To prepare for the role as a Black Ops agent in Haywire, she worked with a Hollywood stunt crew and attended a two-month training camp with a former Israeli intelligence operative.
According to Soderbergh, it was his intention to have Carano – who is a 5-feet 8-inches tall and 143 lbs. – rather than one of her male costars, be the toughest character in the film.
"There was something transgressive about having the woman being the one who is attacked first," Soderbergh recently told Sports Illustrated.
"There's sort of, in movie terms, a popular conception that women are weaker than men and that the only way that they can triumph in a hand-to-hand situation is if they somehow have an advantage from the beginning. ... [Carano's character] is attacked in an unprovoked manner and has to work her way back into winning the fight. With someone like Gina, you can pull that off and have it be believable. She can really break you in half."