Boxing legend Floyd Mayweather has hit out at a welterweight all-time rankings that saw Sugar Ray Leonard punch above 'Money' to take the number one spot.

The 50-0 fighter told YouTube channel FightHype that a friend had sent him a list of the best welterweights to ever grace the ring.

“They had Sugar Ray Leonard number one,” he explained. “Like I said before, he was the guy that paved the way for myself. But how can you have a guy ranked number one when his first loss was to a lightweight, Roberto Duran?”

The rankings were compiled by big names from the fighting media world, something the 43-year-old laughed off.

“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 got to really do your homework before you speak on certain things about boxing.”

The list has inspired boxing fans over at Ranker to compile their own rankings system, but just a pre-warning, if you’re a former five-weight world champion who once beat UFC’s Conor McGregor in a lucrative crossover bout, you may want to look away now.

30. Jack Britton

Born in New York in 1885, Britton's professional record reads 104 wins to 29 defeats.

29. Saúl Alvarez

Better known as Canelo Alvarez, the Mexican has won 53 of his 56 fights, with his only loss coming against Mayweather in 2013.

28. Barbados Joe Walcott

No relation to Theo, or so we know of, Bajan-born Joe adopted Barbados to his name to differentiate himself from an American fighter.

27. Fritzie Zivic

The son of Croatian and Slovenian parents, the Pittsburgh-born puncher was world champion from October 1940 to July 1941.

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26. Tommy Ryan

A double-weight world champion, Ryan lost just twice in an illustrious 105-fight career.

25. Charley Burley

Archie Moore, a light-heavyweight champion who dropped down to middleweight for the pair's 1944 fight, said Burley was the greatest fighter of all time.

24. Jimmy McLarnin 

BoxRec has the Irish-Canadian welterweight down as the 11th best pound-for-pound boxer of all time.

23. Ted "Kid" Lewis 

A member of the International Jewish Sports Hall of Fame, Lewis won 192 of his 238 professional bouts.

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22. Roy Jones Jr. 

Junior was named as Ring Magazine Fighter of the Year in 1994.

21. Barney Ross

A fighter in and out of the ring, the New York-born boxer was awarded the US military's third highest honour the Silver Star for his heroics in the Second World War.

You can see who made 20-11 in this list here.