According to TMZ, the two have developed a strong relationship over the past few months.
According to our sources, Mayweather asked Bieber four months ago to join him in Las Vegas for the Miguel Cotto fight ... and Bieber, a huge boxing fan, jumped at the opportunity.
We're told Floyd and Justin became friends after Floyd saw Justin's movie, "Never Say Never," and reached out to his camp. According to our sources, Floyd decided he wanted to mentor Justin and the two developed a relationship.
Our sources say Mayweather tried to impart his work ethic on Justin, basically telling him he could develop the same level of "greatness" Floyd achieved ... if he worked as hard as Floyd did.
Justin has gained new respect for his mentor and exclaims that he is just misunderstood.
He also was quoted saying that Mayweather is a "hard-working and clean-cut guy."
We hope this friendship lasts and Mayweather becomes an important part of Justin's life. Maybe he will even show him the secret to his haymaker!