Nick Calathes has been suspended for 20 games after being found to have violated the NBA's anti-drug policy.
The league announced that the Memphis Grizzlies rookie guard has tested positive for Tamoxifen, a substance which is banned by the NBA.
According to Yahoo! Sports, the drug was found in a supplement that the 25-year-old had been taking.
Calathes's suspension starts this evening, when the Grizzlies face the Oklahoma City Thunder in the first round of the playoffs.