Russian cyclist Victoria Baranova has become the latest Olympic athlete to be sent home for doping.
The 22-year-old, is ranked second in the world for the women's keirin and was expected to be one of Victoria Pendleton's main rivals at London 2012.
International Cycling Union spokesman Enrico Carpani said: "It is the result of a test carried out by the IOC before the Games. She has admitted to taking a banned substance and was sent home two or three days ago.
"We have been working closely with the IOC and we are very happy with this collaboration, which strengthens our fight against doping."
Baranova tested positive for testosterone.
