Former undisputed cruiserweight and heavyweight champion Evander Holyfield gave his opinion on Floyd Mayweather's remarkable career.

Mayweather retired last August, unbeaten in his professional career, with the unbelievable record of 50-0.

In his last fight, he claimed a stoppage victory over boxing debutant and UFC superstar Conor McGregor.

During his 21 years in the professional ring, Mayweather Jr. won titles at five weight classes - super featherweight, lightweight, junior welterweight, welterweight, and junior middleweight.

What Evander Holyfield dislikes in the whole situation is that "Money" Mayweather has never been the undisputed champion in any of these divisions.

In 2015, Mayweather was close to winning all the belts, when he defeated Manny Pacquiao in a WBC, WBA, and WBO welterweight title clash. Anyway, he refused to pay a sanctioning fee and he was stripped of the WBO belt.

Although Mayweather has the reputation of one of the world's best and is the self-announced "TBE", Holyfield feels he has not done enough.

"My whole thing, he is a great fighter. But to actually say that (he's beaten everyone), you've got to be the undisputed," Holyfield explained to Kevin Iole of Yahoo Sports.

"You need to get all the belts at one time and let everybody know that I beat everybody who had a belt and I am undisputed. You can't just say 'I got this WBC belt, I got this WBC belt and I got this WBC belt,' and all of them are WBCs and you don't have the rest of the belts to say you are undisputed.

"The whole big thing is, it's not just this one belt - it's all of these other belts. I wanted to be undisputed, where you can say that I am the undisputed champion of the world.

"Ever since (Muhammad) Ali left, there wasn't an undisputed champion until (Mike) Tyson was the first one to be made undisputed, then Buster Douglas, then me, then Riddick Bowe and then Lennox Lewis. Lennox was the last one (at heavyweight).

"That was five guys who took the time and said 'I don't just want to be one of the champions - I want to be undisputed where everyone knows at that time that I was the very best.

"That's the only thing that Floyd is missing, because he was never the undisputed world champion in any weight division."