Tommy Fury went from using his hands to using his pipes after beating Jake Paul on Sunday ... singing his heart out with his brother, Tyson, in the locker room to celebrate the huge win.
TNT was the happiest guy in the world after going 8 rounds with the Problem Child in Saudi Arabia ... and the man of the hour received a hero's welcome after exiting the ring.
"There's only one Tommy Fury," the crowd chanted as Tommy entered the room. "Walking along, singing a song, walking in a Fury wonderland.