Anthony Joshua is in for a south of the border surprise come Saturday night ... because his opponent, Andy Ruiz, says he's gonna put DEM FREAKIN' HANDS ON AJ, all for the pride of Mexico.
Ruiz was a late add to the fight following Jarrell Miller's positive drug test, so most people aren't giving the new challenger too much of a shot against the undefeated heavyweight king Joshua.
We spoke to Ruiz and he told us he knows he's being taken lightly, and that's his biggest weapon.