What movie is this?

So I've been trying to remember the name of a movie, it's about these two guys who owe a debt to I think a mobster from betting on underground boxing or mma or something like that, but they can't afford to pay it off so they try to find someone to enter into the fight and they find a gipsy that is really good at fighting. Well he kept winning so the mobster tried to make the gipsy not fight by killing his mother and burning the trailer she lives in, and at the end of the movie the first two guys try to go find him and he was gone along with the rest of the gipsys. Some of the details may be a little incorrect but for the most part that's the movie