Rocky fought Drago in the Soviet Union ... and Kelvin Gastelum's fighting Robert Whittaker in Australia -- and just like "Rocky IV," Gastelum says he's gonna beat the hell outta the home-country hero.
TMZ Sports talked to Gastelum -- whose favorite boxer is Rocky Balboa (yes, we all know he's a fictional character) -- days before fighting Whittaker, the UFC middleweight champ ... in his home country.
Gastelum lives in California ... and traveled 8,000 miles for this fight. So, he's expecting everyone on the continent to be rooting against him.