Floyd Mayweather Jr has insisted that he is not in any way hesitant about entering retirement because he has "nothing left to prove in the sport of boxing".
Mayweather recorded a unanimous points decision victory over Andre Berto on Saturday to draw level with former heavyweight champion Rocky Marciano with a 49-0 career record.
The American had said before the fight that it would be his last, and he was in no mood to change his mind afterwards.
When asked if he would tempted into returning for a 50th fight, he responded: "My career is over. It's official. I'm financially secure and I'm in good health.
"You've got to know when it's time to hang it up, so I think it's about time for me to hang it up. I'm close to 40 years old, I've been in this sport 19 years, been world champion for 18 years, I've broken all records.
"There's nothing left to prove in the sport of boxing."
Should the 38-year-old perform a U-turn and return to the ring, it will not be the first time he has done so, having previously come out of a 21-month retirement in 2009 in order to fight Juan Manuel Marquez.