Anti-Doping Agency late last week that a sample came back positive from a May 16 out-of-competition test. Gay wouldn't reveal the substance in a phone conversation from Amsterdam on Sunday, but he said he was notified by the U.S. American 100-meter record holder Tyson Gay, who had promoted himself as a clean athlete, tested positive for a banned substance and said he will pull out of the world championships next month in Moscow.
