Floyd Mayweather Jr is adamant that he will not renege on his promise that Saturday's bout against Andre Berto will be his last, citing health concerns as the reason for his decision.
Mayweather has a 48-0 record through a stellar career and has maintained that his welterweight title defence against Berto (30-3) will mark the end of his time in the ring.
Many have tipped the American to go back on his word and attempt to rack up 50 victories, but the 38-year-old has no plans to fight on after the showdown in Las Vegas.
"Number 49 is my last fight. No one is in my shoes. My health is more important," he said.
"If you stick around anything too long, 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."
The fight will be Mayweather's first since he defeated Manny Pacquiao in the richest bout in boxing history in May and he once again defended his opinion that he is the best ever.
"I'm not Nostradamus but if you go look at an old interview, I talked about Pacquiao, what they were going to say, what they were going to do and how that fight was going to go," he added.
"Everybody that said throughout the years that I was a coward, I was scared, 'he couldn't beat Pacquiao'. They gave him this. They gave him so many accolades and he's 'an all-time great'.
"But all these people had to eat their words. So if he's an all-time great, then what does that make me? If they're saying he's the fighter of the century, what does that make me?"