"Sugar" Shane Mosley's first loss came in 2001, and he was never really the same guy after that.
His last two fights ended especially badly. Last year, he lost to Manny Pacquiao; then, he went out and got destroyed by 21-year-old Saul Alvarez a month ago.
With those unfortunate blemishes on his record, according to Dan Rafael of ESPN, the 40-year-old has decided to hang up his gloves.
Mosley thanked his fans on Twitter today:
Good Mourning everybody Just want to thank you for showing me so much love.Had a great career and loved every moment of it. win,lose or draw
— Shane Mosley (@SugarShaneM) June 4, 2012
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"I'm going to leave it alone," he told ESPN. "I'm good. I'm going into the promotional world, I'm training my son (21-year-old amateur Shane Mosley Jr.). It was a helluva career. I'm happy for all the great memories and all the great fighters that I fought. Now it's time give back. I'm ready to train my son full-time now."
After losing to Alvarez (who is the same age as his son), Mosley decided that he had to call it quits.
"That's life, that's getting older," he said. "When you get older, you see what happens. You think you can do things. You see stuff that you think you can do, that you want to do, but you just can't do it anymore."