Team GB's Victoria Pendleton has won silver in the women's sprint.
The 31-year-old was hoping to secure gold in her final race before retirement, but she was defeated by Australian Anna Meares.
Pendleton thought she had won the first out of a possible three races, but she was demoted after she was adjudged to have interfered with Meares.
That handed the Australian the advantage and after a cagey opening to the second race, Meares broke clear to secure gold.
China's Guo Shuang won the bronze medal.
