WASHINGTON - US sprinter Tyson Gay, the fastest man over 100m this year, has failed a dope test, according to reports in the US media on Sunday, with the 30-year-old immediately withdrawing from the world championships. Gay, the 2007 world champion, was allegedly informed by the United States Anti-Doping Agency (USADA) on Friday of his failed test. Gay has said he would pull out of August's World Championships in Moscow. USADA said Sunday that the 30-year-old had removed himself from further competition but that his B sample has yet to be tested. "In response to Mr Gay's statements, USADA appreciates his approach to handling this situation and his choice to voluntarily remove himself from competition while the full facts surrounding his test are evaluated," USADA said. –AFP