Abigail Breslin -- Pulls a Juan Marquez and KOs a Stunt Guy

Who knew "Little Miss Sunshine" Abigail Breslin was such a bad ass? The 16-year-old actress sent a stunt man straight to the medic on the set of her new film ... after SHE PUNCHED HIM IN THE FACE!!!!

Abigail is up in Canada right now filming "Final Girl" -- a thriller directed by Tyler Shields about a super tough chick who fights off a pack of feral dudes -- and INSISTED on doing her own stunts.

Last week, Abigail was shooting a HUGE action scene where she was hanging out of a car and then "pretending" to knock out her scene partner ... when things got hairy.

We're told Abigail accidentally clocked the stunt guy for real and the punch was sooo powerful, he had to stop filming and was rushed straight to the on-set medic.

Our sources tell us Abigail was extremely apologetic when it happened. And as for the guy ... he resumed filming a short time later ... with a giant black eye.