Cain vs. Old Fart is a fight between Cain and King, who has been entered into the VaizelFight Festival by Ban under the name of "Old Fart". It is the third battle of the first round in the tournament.
After Cain enters the ring for his battle against King, he is shown to still be drunk, while the commentator speculates about the power the two fighters, who did not participate actively during the preliminaries, are hiding.
As the battle begins, King, mentally dedicates his victory to Diane, intending, and imagining himself moving towards Cain instantly and punching him in the face. However, King in actuality, just jogs toward Cain, missing his opponent and punching the air instead; much to the audience's disappointment. Cain readies a punch in response, but instead merely bonks King on the head. This "attack", King comments, was very strong. King then uses his ability, "Disaster", to trigger Cain's rheumatism and unintentionally forces the alarmed elderly man to punch the Deadly Sin out of the ring.
Proclaimed the winner, Cain claims to be surprised, and that he lost control of himself during the fight. As King expresses his disapointment about losing, Love Helm, the referee, declares the next battle to be against Meliodas and Ban.