Mayo was late for a game-day shootaround and was taken out of the starting lineup starting November 20, 2010. On a return flight to Memphis from Los Angeles, Mayo was involved in a fight with teammate Tony Allen over a debt from an in-flight card game. On January 27, the NBA suspended Mayo for 10 games following a positive test for the steroid dehydroepiandrosterone (DHEA), which violates the league's anti-drug program. Mayo blamed an over the counter supplement that he didn't know was banned by the NBA for the positive test, but he declined to say which supplement he used. He later said an unnamed energy drink he bought at a gas station contained the banned substance.