Yamasaki oversaw a female flyweight bout between Valentina Shevchenko (15-3) and Priscila Cachoeira (8-1) in Belem, Brazil. Shevchenko was a massive 10-to-1 betting favorite going in and dominated Cachoeira.

Yamasaki stopped the contest at 4 minutes, 25 seconds of the second round, after Cachoeira tapped out to a rear-naked choke. Many observers felt the fight should have been stopped well before then, as Shevchenko hurt Cachoeira badly with strikes.

"Priscila Cachoeira, you showed so much heart and toughness in that fight," White wrote in an Instagram post. "I'm honored to have you fight in the UFC. Unfortunately, the ref is there to protect you and Mario DID NOT do that.

"This isn't his first disgusting performance in the Octagon. Another unfortunate thing is that I can't do anything about it, only the Brazilian commission can and I am hoping after this scary, incompetent showing he hopefully will never set foot in that Octagon again."

White also referenced the bout's total strike count. According to Fightmetric, Shevchenko had outlanded Cachoeira in total strikes 230-3.

Yamasaki has been at the source of controversy before. He publicly apologized for a late stoppage of a UFC heavyweight bout between Derrick Lewis and Travis Browne in February 2017.

Four months later, UFC lightweight Michael Chiesa tried to appeal a loss to Kevin Lee, after Yamasaki stopped the bout due to a choke, even though Chiesa didn't tap.