In 1986, at the age of 22 Yamasaki began training in Brazilian jiu-jitsu under 5th degree black belt Marcelo Behring (a black belt under his father Flavio Behring and Rickson Gracie[1]), who began teaching jiu-jitsu at the same gym in São Paulo where Yamasaki taught judo.
[3][4] At UFC 142 Yamasaki controversially disqualified Erick Silva for illegal blows to the head of Carlo Prater.
[9][10] Dana White has previously repeatedly called for Yamasaki to be precluded from refereeing future UFC events, due to numerous similar controversies.
He announced in 2021 that he planned on applying for more regular officiating assignments, as well as taking a judging course organized by the California State Athletic Commission.
[12] Yamasaki lives between São Paulo, Brazil, and Bethesda, Maryland, with his wife and children, where he co-owns and operates a chain of Brazilian jiu-jitsu schools.