Mayweather retained his WBC title by beating Hatton
American great Floyd Mayweather Jr has announced his retirement from boxing.
Widely considered boxing's best pound-for-pound fighter, Meayweather retires unbeaten with a record of 39-0.
The 31-year-old's final bout was in Las Vegas last December when he knocked out Britain's Ricky Hatton to retain his WBC welterweight crown.
Mayweather's retirement is a blow for Manchester's Hatton, who had been targeting a rematch with the five-weight world champion in 2009.
In May last year, Mayweather said he would quit boxing after beating Oscar de la Hoya in Las Vegas to claim the WBC light-middleweight title.
He subsequently changed his mind and was expected to meet fellow American De la Hoya in a rematch on 20 September.
"This decision was not an easy one for me to make, because boxing is all I have done since I was a child," Mayweather said in a statement.
"These past few years have been extremely difficult for me to find the desire and joy to continue in the sport," he said.
There comes a time when money doesn't matter. I just can't do it anymore
"I am sorry I have to leave the sport at this time, knowing I still have my God-given abilities to succeed and future multi-million dollar paydays ahead, including the one right around the corner (the proposed De la Hoya fight).
"But there comes a time when money doesn't matter. I just can't do it anymore. I have found a peace with my decision that I have not felt in a long time."
Mayweather won a bronze medal at the 1996 Olympics and went on to win world titles at super-featherweight, lightweight, light-welterweight, welterweight and light-middleweight.