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Under-fire Comrades Marathon winner Ludwick Mamabolo has denied using a banned substance to win the 89km race earlier this month.
He says he did not take any banned substances - only products he has used in previous years at Comrades.
He told the Sowetan that he was confident he would be found not guilty.
The SA Insitute of Drug Free Sport announced on Tuesday that he had tested positive for the banned substance methyl-hex-aneamine.
The institute's CEO Khalid Galant said it was possible that the substance could have been contained in an energy drink.
Mamabolo's blood & urine samples will now be sent for further analysis to the doping control laboratory in Germany.
The results are expected in the next four weeks.
If found guilty, Mamabolo could lose his title and R300,000 rand prize money.
