KEY BISCAYNE, March 27 Guillermo Canas of Argentina, once a nemesis to Roger Federer, has announced his retirement from tennis.

The 32-year-old Canas said on Friday he decided to retire rather than undergo a fifth operation on his right wrist.

He has been battling pain in the wrist for more than a year and hasn't played in a tournament since July.

Canas made the announcement at the Sony Ericsson Open, where he's remembered for upsetting the top-ranked Federer in 2007. Canas also won when they met at Indian Wells earlier that same month, ending Federer's 41-match winning streak.

“I beat the most talented player in the world,” Canas said. “For me it was unbelievable. And then to do it again 10 days later was like a dream for me.”—AP