Floyd Mayweather has lashed out at a recently released all-time best welterweights list after being ranked behind Sugar Ray Leonard.

The 43-year-old was fuming with his position in the rankings, claiming that Leonard doesn't deserve the top spot because he lost to Roberto Duran, a lightweight boxer, during his career.

Looking at Mayweather's career, it's easy to understand why he might feel a bit miffed about not coming first. Arguably one of the best to ever grace the ring, Mayweather 'retired' from the sport with an incredible professional career record of 50-0.

Despite his anger, "Money" hasn't actually told anyone where exactly in the rankings list he was placed, but judging from his reaction, he wasn't treated very kindly.

Speaking to FightHype, Mayweather ranted: "It was crazy, someone sent me something about 'The Best Welterweights.'

"They had Sugar Ray Leonard No.1.

"Like I said before, he was the guy that paved the way for myself.

"But how can you have a guy ranked No.1 when his first loss was to a lightweight, Roberto Duran?

"And then they also talked about me facing [Juan Manuel] Marquez, which was at catchweight of 144lbs.

"But this same guy, Marquez, knocked out their No.3 ranked welterweight - because they had Pacquiao No.3. He got knocked out by Juan Manuel Marquez."

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"They were trying to say that basically he [Marquez] was too small for me. But he wasn't too small for Pacquiao.

Mayweather continued his tirade, explaining: "It's crazy how all these ratings go nowadays. Of course, fighters are always gonna say, 'I would've done this, I should be ranked here.'

"But a lot of these so-called boxing experts, it's just crazy how these guys are experts.

"If you're an expert, you've gotta really do your homework before you speak on certain things about boxing."

Perhaps it was for the best that Mayweather never lost a fight during his professional career, because if anything, this shows that he really doesn't take losing very well.

If he gets this worked up over a list, imagine how bad it'd be if he lost in a ring.