Ex-MMA fighter Javier Baez didn't just body slam a crazed knife-wielding assailant; he also "choked him out" ... telling TMZ his 15 years of pro training finally came in handy in the streets.
As we reported, the shocking clip making the rounds online shows Javier's attacker, Omar Marrero, didn't stand a fighting chance when he charged ... even though he had a 14-inch knife in his hand.
Javier tells us it all started while he was minding his biz, sitting in his car and talking to his fiancee -- he says that's when Marrero banged on his car window, shattering it.