The prospect of a blockbuster fight between boxing legend Floyd Mayweather Jr and UFC star Conor McGregor has had tongues wagging for months, but on Wednesday it became a reality.

It was announced via social media that a showdown had been agreed for August 26 in Las Vegas, meaning the speculation can stop and the trash talking can begin... if it has not already.

But this is a deal that has had its fair share of critics, with highly respected figures branding the fight an "embarrassment", while some fighters have been keen to get on the undercard.

So here is a round-up of what has been said about what is already one of the most talked about fights in history.

OSCAR DE LA HOYA

"Boxing is boxing and MMA is MMA," De la Hoya, a former boxing world champion in six weight divisions, told Omnisport.

"They're two separate sports. It would be a joke, it would be an embarrassment for boxing if an MMA fighter were to go into the ring, it would be a no contest.

"It would be the same thing if a fighter went into the octagon. It would be an embarrassment for MMA. 

"I just feel that these are two separate sports and you have McGregor who is the best at what he does, and you have Mayweather who is the best at what he does."

MIKE TYSON

"[McGregor] doesn't win in a boxing match," former undisputed heavyweight champion Tyson told Sirius XM 93.

"I don't believe it can ruin boxing at all. Only way it can ruin boxing is if McGregor goes and boxes Floyd because he's going to look really ridiculous boxing him.

"But if he goes in there with the UFC stuff, now this could be pretty interesting."

SUGAR RAY LEONARD

"It's two different sports trying to be one sport," said boxing great Leonard. "Would it sell? Yes it will sell.

"There's a curiosity which is a factor. But it won't be what people are anticipating. It is not a fight which will please the boxing purists.

"We live in a different time now with social media and what have you. The purists, the boxing fans, would they like it? No, I don't think so. But fans in general, the sports fans, they wouldn't miss it for the world."

DANA WHITE

"A lot of things make this fight intriguing but the reality is this: Anybody who has ever seen Floyd Mayweather, he's this big [gesturing at the American's small size]. Conor McGregor is huge," UFC president White told Conan.

"He's in the prime of his career. Floyd is 40. Floyd always had problems with southpaws, Conor is a southpaw and Conor hits hard. When Conor hits people, they go.

"Floyd's definitely not knocking him out, that's for sure. I'm not saying that Conor would win this boxing match but it sure makes it interesting."

ANTHONY JOSHUA

"Get me on the undercard!" said heavyweight champion Joshua. "Listen that's legendary s***, that fight will go down in history!"