American sprinter Tyson Gay tested positive for banned substances twice this year, the Associated Press reported Friday.
Gay announced he tested positive for the first time earlier this month.
According to an AP source, Gay tested positive at the U.S. championships in June, where he won the 100 and 200 meters.
Gay will not appear at next month's world championships, and his victories at the U.S. championships will likely be vacated.
Another source told the AP that positives in a short period of time is typically evidence of an athlete not aware that he or she had been using a banned substance.
The substance has still not been revealed.