Tom Danielson reveals failed doping test for testosterone

American Tom Danielson has tested positive for banned drug testosterone and announced the result on Twitter. The cyclist for Cannondale-Garmin, who testified in the Lance Armstrong USADA case, made a series of posts on Monday morning explaining what happened and insisting he is innocent.

Danielson already served a six-month ban after testifying in the US case against Armstrong. During it, he admitted that he blood doped in his with the Discovery Channel team.

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"Tonight has been one of the worst nights of my life," Danielson wrote on Twitter. "While I was eating dinner with my team the night before Tour of Utah I received a call. For USADA notifying me that a out of competition test I gave July 9th has tested positive for, from what I understand, synthetic testosterone.

“I have not taken this or any other banned substance."

Danielson, 37, was due to start the Tour of Utah today in the USA. He won the last two editions of the race, in 2013 and 2014, in the country's southwest. He also placed second in last year's Tour of Colorado and eighth overall in the 2011 Tour de France.

In recent years, however, he mostly worked as a domestique for Cannondale's star riders Ryder Hesjedal, Andrew Talansky and Daniel Martin.

The positive anti-doping test could end Danielson's professional career.

"I spoke with them and my team and I will have to sit out the Tour of Utah as I wait for the B sample," Danielson added, "as well as look into all the possible ways that could have produced this result."

Danielson was one of 11 former team-mates who testified against Lance Armstrong and helped bring him a lifetime ban in 2012. The ban also saw Armstrong stripped of his seven Tour de France titles.

As part of his six-month ban, Connecticut-born Danielson was stripped of his results from March 1, 2005 to September 23, 2006. He lost the Tour of Georgia and Tour of Austria overall, as well as a stage victory and sixth overall in the Vuelta a España.

"I feel incredibly hurt, frustrated, and angry by this," Danielson said. "I don't understand how or why this happened and still can't even accept this is true."