Russian track cyclist Victoria Baranova has been sent home from the Olympic Games after testing positive for testosterone.
Cycling's world governing body the UCI confirmed the 22-year-old, a European individual sprint bronze medallist, would take no part in London 2012.
Baranova was one of three Russian women selected to compete in cycling at the Games, and had been due to race in the keirin today.
A spokesperson for the UCI told Press Association Sport: "She is already home. She was sent home by her National Olympic Committee yesterday morning."
Baranova, who is coached by her father Alexey Baranov, has been competing on the international circuit for four years despite her young age.
She has collected bronze medals in three World Cup team sprint events, and another in the individual sprint in Cali, Colombia, last December.
In July 2011 she was crowned European Under-23 keirin champion.