Portland Blazers' shooting guard Brandon Roy has decided to retire after just five seasons due to serious knee problems, reported the Oregonian newspaper on Friday.

The NBA's rookie-of-the year in 2007, 27 years old, did not report for Portland's first day of training camp on Friday.

He discussed his degenerative knees with team doctors on Thursday and made the retiring decision after that.

Roy has been dogged by problems since his college days and lacks cartilage between the bones on both knees. He has undergone a half-dozen knee surgeries, including last January on both his knees.

The guard averaged 19 points, 4.7 assists and 4.3 rebounds over his career, but did not play for long periods last year.