May 26 (UPI) — World Heavyweight Champion Roman Reigns and his rival Jacob Fatu had a war of words leading up to their upcoming title match on WWE Raw.

Reigns, who was celebrating his 41st birthday on Monday, signed the contract to face his cousin Fatu in a Tribal Combat match for the World Heavyweight Championship. The high-stakes bout will take place at Clash in Italy on Sunday.

A Tribal Combat match has no rules and the loser must acknowledge the winner as the Tribal Chief. The Tribal Chief is the leader of Reigns’ and Fatu’s storied wrestling family.

Reigns signed the contract quickly and told Raw general manager Adam Pearce to exit the ring along with security so that he could be alone with his cousin.

“Jacob if you beat me, then you become the head of the table. You become the shot caller. You lead and I follow,” Reigns said before stating that he was going to dog walk Fatu.

“I’m going to domesticate you. If you can’t beat me, you will serve me and you will learn from me. And in time Jacob, you will love your Tribal Chief,” Reigns continued before Fatu said he was going to make his family acknowledge him.

Clash in Italy will air Sunday at 2 p.m. EDT on the ESPN app in the United States and on Netflix internationally.