Miss USA 2014 Nia Sanchez -- Hot Bod AND Killer Instincts

Miss USA 2014 is a total knockout.

Turns out 24-year-old Nia Sanchez -- who won the title over the weekend -- can put you in a coma if you cross the line uninvited ... cause she has a fourth-degree black belt in tae kwon do (see below).

During the competition, Sanchez brought up her martial arts training twice during interviews, which she began practicing when she was 8.

Sparring partners ... take a number.