He may be friends with the undefeated professional boxer, but Justin Bieber does not think Flyod Mayweather will knock out UFC champion Conor McGregor.

Mayweather, who has won 26 of his 49 fights by knock out, recently stated that it would be a victory for McGregor if he did not knock out the MMA fighter when the pair meet in Las Vegas on August 26.

He said: "It is a victory for him. If he goes the distance, it’s a victory for him. In my eyes, also."

However, while Mayweather is confident that McGregor will go down, his pal Justin Bieber is not so sure.

Speaking to TMZSports about whether he thinks Mayweather can do it the Never Say Never hitmaker said:

"I don't think so. I think it'll be a good fight."

The unlikely friendship first came to light when the Biebs walked to the ring with Mayweather when the professional fighter was set to face off against Marcos Maidana in May 2014 in Las Vegas.

The singer was also guest at the sportsman's 40th birthday party in February, where he sang his hits What Do You Mean? and Where Are U Now.

Speaking about Mayweather at the party Bieber said: "I love this guy. I look up to him. Give it up for the champ."