The league announced the suspension Thursday for Mayo's positive test for dehydroepiandrosterone (DHEA). Mayo's suspension will start Friday night when the Grizzlies visit Philadelphia, and he will be able to return Feb. 15, also against the 76ers, in Memphis. He will forfeit $405,109 of his salary.
Mayo said in a statement released by the team that he is extremely disappointed he will miss 10 games as the Grizzlies are making a push for the playoffs. He blamed an over-the-counter supplement that he didn't know was banned by the NBA for the positive test, but a team spokesman said Mayo declined to say which supplement he used.
"It was an honest mistake, but I take full responsibility for my actions," Mayo said in the statement released by the team. "I apologize to my fans, teammates and the Grizzlies organization for regrettably not doing the necessary research about what supplements I can put in my body."
Mayo's agent did not immediately return a message left at his office Thursday.
DHEA is a legal, mild steroid precursor, which means that it isn't a steroid in a bottle, but converts once ingested. Although banned by most sports leagues, it's not controlled as a substance by the Drug Enforcement Agency, which means anyone can buy it.
Mayo was the No. 3 pick overall in 2008 after only one season at USC, and Minnesota swapped him in a draft night deal to the Grizzlies for Kevin Love. Mayo was runner-up to Chicago's Derrick Rose for rookie of the year.
But the guard was moved to the bench earlier this season, starting just 15 of Memphis' 45 games this season. He's been bandied about as possible trade bait even while ranking fourth on the Grizzlies with 12.2 points per game.
Grizzlies owner Michael Heisley said Mayo will continue practicing with the team during his suspension.
"O.J. had a lack of judgment but has shown complete accountability," Heisley said in a statement. "We will continue to support O.J. during this time as we have from the moment he joined the team in 2008. He has unselfishly done everything we have asked of him, and we expect him to grow as a player and a person from this experience."
T.J. Quinn, a reporter in ESPN's enterprise/investigative unit, senior NBA writer for ESPN.com Marc Stein, and The Associated Press contributed to this report.