Australian surfer Ethan Ewing has been told next month's World Surf League event in Brazil will be "your funeral".
The death threat from a Brazillian fan, which also said "here in Brazil, we will kill you" came after the Australian knocked out three-time world champion Gabriel Medina from the recent Surf Ranch Pro in California.
Both were level on 16.67 points in their quarterfinal, with the Australian winning on countback having posted the highest wave of the day with a 9.07.
Medina sent an open letter to the WSL complaining about the fairness of the judging, adding to growing claims the organisation has a set agenda against the "Brazilian Storm" that has dominated men's surfing in recent years.
"Dear WSL, Please understand the importance of this discussion … the surfing community, especially the Brazilian one, has been appalled by the lack of clarity and inconsistency in the definition of grades for many years now, but lately it has been even more shocking," three-time world champion Medina wrote on Instagram.
"It's clear that the judges' assessment is now rewarding very simple surfing, incomplete transitions, and PROGRESSION and VARIETY is being completely taken out of the equation.
"This is very frustrating and threatens the growth of the sport. Fans and sponsors will not accept that this continues and, for the foreseeable future, will end up pulling away as they expect an equal and fair trial for the sport."
Medina's letter stirred up Brazilian fans, who vented on the WSL's social media, targeting world number four Ewing.
"One day, you will compete here in Brazil and us (sic) will remember you. Get ready," one wrote.
"I'm saying again, here in Brazil, we will kill you. Saquarema will be your funeral."
Queenslander Ewing posted the direct message responding: "How good are surfing fans!"
The tour moves to Saquarema in Rio for an event late next month.
Despite their complaints, Brazilian men have won the world title in six of the past eight years, with Hawaiian John John Florence breaking up the run.
They have also won three events this year, with Toledo winning at Sunset Beach, Joao Chianca winning in Portugal and Medina taking the Margaret River title, with Chianca and Toledo sitting two and three in the rankings.
The WSL rejected the criticism and said Medina's comments were "unacceptable".
"Surfing is an ever-evolving, subjective sport and we appreciate a robust debate around the progression of our sport and the criteria used to judge our competitions," a WSL spokesperson said.
"However, it is unacceptable for any athlete to question the integrity of our judges who … are elite professionals."
American Griffin Colapinto won the men's final, defeating Brazil's Italo Ferreira.
AAP
