There was no fairytale ending for retiring boxer Miguel Cotto, who suffered a shock defeat to Sadam Ali via unanimous decision in New York.

The curtain came down on Cotto's glorious 17-year career but not to script as Ali dethroned the WBO light-middleweight champion at Madison Square Garden Saturday. A crowd of 12,391 fans – made up of largely Puerto Ricans – came to farewell the 37-year-old icon (41-6), who stepped into the ring for the 47th and final time.

However, the judges scored the fight 116-112, 115-113 and 115-113 in favour of local Ali (26-1) – an Olympian in 2008.

Afterwards, Cotto revealed he suffered a bicep injury during the fight. "Feeling good. Feeling good with the performance," Cotto said. "Something happened to my left bicep, seventh round. I don't want to make excuses. Sadam won the fight. It is my last fight. I am good, and I want to be happy in my home with my family."

Cotto added: "Thank you for all the fans. I am proud to call MSG my second home. I had the opportunity to provide the best for my family because of the sport."