Hard Work Pays!! (修業の威力！！ Shūgyō no Iryoku!!, lit. "The Power of Training!!") is the thirty-third chapter of the Dragon Ball manga.
The chapter begins with Master Roshi guiding Goku and Krillin to the preliminaries. Since only fighters are allowed in, Roshi bids ado and gives the boys each a pair of fighting outfits, each with his insignia on the left chest.
Once in the room that the preliminaries are being held in, Krillin begins to have doubts about the tournament. The announcer of the preliminaries states that 137 people have entered the tournament, meaning that it will be a trying day for all participants. After he announces the rules of the round, each fighter must draw a number out of a box, which will place them in one of four divisions.
As everyone has drawn their number, the another announcer yells out Goku and a large, Russian fighter's numbers. The match begins, with Goku going through the man's legs. Looking around for the little fighter, the man falls out of the ring, making Goku the winner. Goku jumps out of the ring and tells Krillin not to go all out unless he is up against a powerful opponent. As he tells Krillin this, the monks of Orin Temple come over and pick on him. One of them reveals that he will be fighting Krillin, much to the chagrin of the little boy.
The next match is between Krillin and the bully monk from earlier. When the man comes into attack, Krillin jumps over him and kicks him in the stomach, sending the bully through the wall, making Krillin the victor.