Portland guard Brandon Roy will take a medical retirement according to a tweet from ESPN's Chris Broussard.

Update: This tweet came from Adrian Wojnarowski of Yahoo:

Portland's Brandon Roy has been diagnosed with a "career-ending (knee) injury," league source confirms to Y! Sports. "He's done."

The announcement could come as early as Friday from the former Rookie of the Year.

Roy, who has been battled degenerative knees and had multiple surgeries, has been in the league since 2006 and averages 19 points, 4.7 assists and 4.3 rebounds.

Last season Roy averaged a career low 12.2 points while playing in just 47 games.

Writes Tom Ziller of SB Nation:

A medical retirement will allow the Blazers to remove his contract from the books beginning next season, provided that Roy doesn't return to the court before then and a league-appointed doctor agrees that the All-Star guard is no longer able to play. Roy is owed $64 million over the next four seasons.

Portland players were informed of Roy's decision to seek medical retirement on Friday before the first practice of training camp.

"I couldn't believe it," Blazers forward Nicolas Batum said. "I still can't believe it."

"It's a tough situation," Blazers center Marcus Camby said. "People will say 'Hey, he'll get his money.' But Brandon's a competitor."

Roy, a five-year veteran who helped the team shed its "Jail Blazers" reputation, said he lacks cartilage between the bones in both knees.

NBA spokesman Tim Frank said Roy had not yet filed the retirement paperwork with the league.

If the 27-year-old Roy files for medical retirement, insurance likely would take care of his salary in coming years. His salary would not count against the cap after one year.

There were earlier rumors the Blazers might try to use the league's new amnesty clause on Roy, who signed a five-year maximum contract with the team in 2009. The clause would allow the team to waive Roy without having his salary count against the salary cap and luxury tax.

Acting general manager Chad Buchanan said late Friday that the team was exploring its options concerning both a formal medical retirement and amnesty for Roy.

We're somewhat in the infant stages of going through that process and getting that started," Buchanan said. "But (we're) very supportive of Brandon in all of this. It's a very difficult decision as you can imagine."

If Roy files for medical retirement, insurance would likely take care of his salary in coming years. His salary would not count against the cap after one year.

The Associated Press contributed to this story.