After the NBA suspended Memphis Grizzlies guard Nick Calathes for 20 games because of a positive test for a banned substance, the players union's acting director called the banishment "a true injustice."
The banned substance -- Tamoxifen -- was part of an athletic supplement that Calathes had been using, sources said.
"This discipline is a true injustice," NBPA acting executive director Ron Klempner told Yahoo Sports late Friday night.
Calathes had developed into an important part of the Grizzlies' guard rotation, and will now be lost for seventh-seeded Memphis' Western Conference playoff series against No. 2 seed Oklahoma City Thunder.
The suspension would carry into the 2014-15 season.
"Our collectively bargained program failed this player and this case will certainly be recalled when we return to the bargaining table," Klempner told Yahoo Sports. "In the meantime, we'll file an appeal and allow the process to run its course."
NBA lab results found no traces of synthetic testosterone or performance-enhancing drugs, and as one source told Yahoo Sports, "There was no intent, nor advantage gained here."
Tamoxifen is also on the Major League Baseball and International Olympic Committee's banned substance list, because it has shown to be a masking agent that reduces the side effects of steroid use and increased testosterone production. The drug is generally used in treatments for breast cancer in women.
Calathes' representatives and the NBPA had been part of a process trying to persuade the league office that the positive test didn't violate the spirit or intent of the NBA and NBPA's joint drug testing policy, but the league held firm on the suspension, sources said.
For the season, Calathes, a 25-year-old rookie, has averaged 4.9 points and 2.9 assists per game for Memphis. As part of the Grizzlies' playoff push in the past 10 games, he's averaged 14 minutes, 4.2 points and 2.2 assists per game. Guard Beno Udrih will likely take on a larger role in the series against the Thunder.
Calathes played at the University of Florida, and went to Minnesota with the 45th overall pick in the 2009 NBA Draft. His rights were traded to the Dallas Mavericks, and Calathes played three seasons in Greece and a season in Russia before Memphis acquired his rights in the offseason.
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