Its from the third in the Road Warrior series with Mel Gibson called Beyond Thunderdome.

Master Blaster was my favorite. It was this huge beast of a man but dumb with a little dwarf that rode on his shoulders as the brain. The dwarf was Master, the beast was Blaster. They had the ultimate cage matches to the death and the dystopian population would chant "two men enter, one man leaves" as they entered the thunderdome.

Now I know how young you are lol.