Floyd Mayweather Jr has hinted that he may came out of retirement for one last bout.
He is hoping to reach a half-century of victories and there are a number of boxers who would love the chance to end the Money's record of 49-0-KO26.
The 39-year-old could be willing to return if a nine-figure payday is in line, and he would want it to be a championship fight.
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Keith Thurman and Kell Brook have both been linked with a possible bout against the unbeaten pound-for-pound king, while a rematch with the now-retired Manny Pacquiao - whom he beat by unanimous decision a year ago - has been tipped as an outside chance.
However, there are three men who could set him up for another big payday, and some could offer him a shot at another title.
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The 29-year-old Bolton boy may not offer the championship fight that Mayweather is looking for, and his chances of a shot at Mayweather have taken a massive blow as a result of his knock-out by Saul Alvarez in the WBC world middleweight title fight in Vegas last week.
However, Khan vs. Mayweather would have such huge appeal that it would at least be a pay-per-view fight.
Khan moved up to middleweight for his fight with 'Canelo' Alvarez, but he would have to lose that extra weight were he to face Mayweather.
King Khan has come up against some top fighters, including Chris Algieri and Devon Alexander, but facing Mayweather would likely prove too strong for him.
All of Khan's professional defeats have come against tough opponents, including Danny Garcia back in 2012, and it would seem that he would be adding another defeat to that tally, if Mayweather agreed a fight with the Brit.
For both men, though, it would be an enormous payday.
Broner, a fellow American, could move up to the welterweight division if it landed him a bout with Mayweather.
The Problem's respectable knockout ratio would make it a tough test for the 39-year-old (32-2-KO24), but Broner's two defeats have come against KO specialists Marcos Maidana and Shawn Porter.
Victories over Gavin Rees, Eloy Perez, Vincent Martin Rodriguez and Daniel Ponce De Leon suggest the 26-year-old could take Mayweather the distance.
However, while there are question marks about whether the 5ft 6in fighter could beat the Pretty Boy, there is one man who could prove the biggest challenge:
With a record of 32-0-KO18, Danny Garcia is a prolific welterweight fighter who would really test Mayweather, and if anyone is to beat the undefeated retiree, this is the man.
The Philadelphian's one disadvantage is his short 174cm reach, but Garcia will not be worrying about the smaller issues, as his record speaks for itself.
He would have the confidence to put his record on the line, and prove he is the man that can finally beat Mayweather.
Wins over Robert Guerrero, Lamont Peterson, Lucas Martin Matthysse and Amir Khan, all prove that the undefeated fighter is capable of defeating opponents with fine records of their own, and he has been unfazed by big names like Khan.
The current WBC world welterweight champion would also offer the championship fight that Mayweather is keen to secure if he is to exit retirement.
It is a fight that would attract a massive worldwide audience, due to the genuine possibility that this man could shatter Money's perfect record.
Yet, is Mayweather really up for putting his untarnished record on the line, against a fighter full of confidence? Time will tell.
Who should Mayweather fight if he comes out of retirement? Have your say in the comments.