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Don't let the gray braids fool you -- Willie Nelson is one tough octogenarian.  The country legend, who's turning 81 this week, celebrated his latest accomplishment Monday night -- accepting the title of Master with his fifth-degree black belt in the modern Korean martial art of Gong Kwon Yu Sul. 

The Austin American-Statesman says Nelson's teacher, Sam Um, praised his oldest student for his dedication and commitment to the practice, which Willie has been studying for the past two decades. 

During the ceremony Willie received a certificate and a scroll along with birthday wishes. 

Those attending the event not only congratulated Nelson, but sang "Happy Birthday" to him.  And Willie was generous as well, posing for pictures and signing autographs after the ceremony. 

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