Canelo Alvarez has warned Jake and Logan Paul they risk dying in the ring if they continue boxing.
The brothers have both fought professionally with younger sibling Jake competing three times against a fellow YouTuber, a former NBA star and a former UFC wrestler.
Logan meanwhile made his professional debut against KSI in 2019 and will take on Floyd Mayweather in an exhibition bout next month.
But Alvarez, who takes on fellow super-middleweight world champion Billy Joe Saunders on Saturday, believes no such celebrities should be allowed to box professionally.
"They could get them killed. This is not a soccer game, they could get them killed," he said in an interview with Graham Bensinger.
"Why do they give licences to people who have never in their life even thrown a punch?
"If there's a death, the commission will be responsible. Why? Because they issued the licence for the fight.
"I truly believe that it's a lack of respect. It's all based on money. It's all for money. I'm focused right now on other projects.
"I have other stuff going on, and I would invite him (one of the brothers) for a sparring session so that he truly knows what it's all about.
"For true fighters, I do believe it is a lack of respect."
Jake Paul is planning to fight again this year and has named UFC star Nate Diaz as his prime candidate. He wants to use the welterweight as bait to lure Conor McGregor back to the ring.
"I think people will immediately write me off but they're going to tune into watch," Paul told ESPN.
"It's two massive names and it's a massive pay-per-view. When people see me obliterate him, their jaws are going to drop, they're not going to know how to react and they're going to think it's rigged again.
"At that moment in time, I'll be undeniable to fight Conor McGregor because I beat the guy who beat him.
"The Jake Paul vs Conor fight is a massive fight so I'm like why wait? I don't need to be in this sport forever, I don't need 100 fights so why wait, let's do it right away."
