WBO middleweight champion Billy Joe Saunders is so confident that Floyd Mayweather Jr. will blow out Conor McGregor is five rounds - that he's willing to stake his life on it.

Mayweather, 40 years old, breaks a two year retirement on August 26th, when he returns to the ring to fight UFC champion McGregor in a junior middleweight contest, and 10 ounce gloves. The T-Mobile Arena in Las Vegas will play host.

McGregor is a massive underdog, with not a single professional fight under his belt.

Mayweather is 11 years older, inactive for two years, the smaller fighter and possesses less power - but many experts are still predicting a complete mismatch that is unlikely to last beyond the first six rounds.

McGregor, while a pound-for-pound fighter in mixed martial arts, will now go up against one of the best defensive fighters in the history of the sport.

The only way McGregor can win, says Saunders, is if the fight is completely fixed with Mayweather taking a dive.

“It’s impossible for Conor McGregor to land a glove on Mayweather. This will never, ever, ever happen. The only way something like this would happen [would be] if it was a big fix, and Floyd let him [McGregor] beat him. And that is never going to happen – there is too much legacy. It is just never going to happen," Saunders told Talk Sports.

“I’m confident enough to say that I’d be willing to let a surgeon cut my heart out, keep it alive and put a £1 bet on that Conor McGregor gets beat in five rounds. And if he don’t, then put a knife in my heart."

Saunders will return to the ring on September 16th, when he makes the second defense of his title against talented contender Willie Monroe Jr. at the Copper Box in London. BoxNation and BT Sport will televise.