Jake Paul has received support after allegedly refusing to agree to be drug tested ahead of his fight with Tommy Fury.
Fury's dad John claimed last week that the YouTube star had insisted there was no clause in the contract relating to testing.
And former UFC star Chael Sonnen believes only "a fool" would have agreed.
“He [ Jake Paul ], now within four fights, has the leading family of boxing having their youngest protege begging and jumping through hoops to get on the docket with him. I mean, there’s a real brilliance in everything that Paul did," he said on his YouTube channel.
"But what Paul would not do is agree to VADA. VADA stands for Voluntary Anti-Doping Agency. Now, you take that however you want and quite frankly, I don’t think you’re going to get a different result if Paul p***** in the cup or if I p** in the cup for him.
"Nobody should do VADA. VADA should not have the doors open. It is the most ridiculous thing. Why would you ever, ever offer to put yourself under scrutiny? That is a fool’s move.
"You get absolutely nothing for it, and you potentially get suspended if you did agree to do it. I’m only sharing this with you because I know how it looks for Paul and I know how it looks for other people who publicly refuse to do VADA.
"You are still under state sanctioning. You are still under the promotion sanctions should they want to step in and do it. There still is a testing level. You’re just not volunteering to go an extra step – and only a fool would."
Mirror Fighting has contacted Paul's representative for comment.
Fury and Paul clashed at a press conference this week which was overshadowed by John's vulgar remarks.
BT Sport were forced to issue an apology after the 57-year-old claimed his son would "f*** Jake Paul's girlfriend like a dog" after the fight in Florida.
And last week John told Rob Moore : "[There are] all kinds of stuff in the contract; you've got to do this and you've got to do that.
"I could go into it more and more but I don't want to bore people with the politics. They wouldn't sign up to the VADA testing as well.
"That bothered me a little bit because I wanted that in the contract, but they wouldn't do that. I'm not even bothered about that, because of what they're gonna do, they're gonna do anyway.
"We just want the fight because we know we can win it. People think that Tommy's getting paid to lose, they're joking. A Fury would rather be put do death than go down that road."
