Floyd "Money" Mayweather's decision to fight his last professional fight in September seems to be as fixed as the Northern star with the pound-for-pound king believing there is nothing left for him to accomplish in the field of boxing.

Mayweather will fight against Andre Berto in his farewell fight on 12 September at the MGM Grand in Las Vegas, but critics have ridiculed him for choosing a pugilist, who has lost three out of his last six fights. Boxing fans were anticipating an Amir Khan vs Mayweather clash, as the British boxer was said to be the number one contender to fight the American.

Some experts and critics feels that Mayweather chose Berto, an easier opponent, to maintain his unbeaten streak.

Mayeather's professional record has been top notch, which makes Berto an obvious underdog, but "Money" is fully aware of Berto, who will come fully prepared to break his unbeaten streak.

"He's got nothing to lose, and when you've got a guy that's put in a situation with nothing to lose, it makes him work that much harder," Mlive.com quoted Mayweather as saying.

"He's got a chance to be one of the top guys in the sport when I'm through. So does he want to dethrone Floyd Mayweather? Absolutely."

"Like they say in football, 'Any given Sunday.' I say 'Any given Saturday.' Anything can happen," added Mayweather.

So, if Mayweather defeats Berto his his last professional fight, the champion boxer will remain undefeated and equal Rocky Marciano's record of 49 wins and 0 losses.

Mayweather, who has been in perfect shape throughout his career, hinted health as one of the reasons for his decision to retire.

"My health is more important. Anything can happen. I'm not really worried about losing, but I want to have a sharp mind. You can make a lot of money, but you still want to be able to talk, walk and have a sharp mind," said Mayweather.

Mayweather has been a champion for a number of years now, and his biggest test was expected to come against Pacquiao, who cameup second best against the American. With it, Mayweather also pocketed a whopping $220million.

There were even talks regarding a possible rematch between Pacquiao and Mayweather, with the Filipino having shown some interest of late as well. But, Mayweather, who did not have a rematch clause in his fight of the century contract, will not fight anyone after his September fight.

Mayweather, the highest paid sportsperson in the world, feels that he has achieved everything.

"There's really nothing else to accomplish," said Mayweather.

Other contenders, who could have fought the American in his 50th fight were Saul "Canelo" Alvarez and Miguel Cotto, but Mayweather does not feel the need for a 50th fight.

"If I'm through at 49, why would I fight one of them in my 50th fight?"

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