Great Britain's Victoria Pendleton was denied a golden goodbye and a third Olympic title in dramatic fashion as her perennial rival Anna Meares claimed sprint gold at the London 2012 velodrome.
Pendleton's superior pace saw her cross the line first in the first bout, but she strayed from the sprinting lane under supreme pressure from the physical Meares and commissaires awarded the Australian victory.
Meares came to a near halt at the end of the first of three laps in the second race, forcing Pendleton to the front. The Australian rounded Pendleton on the outside and the Briton could not respond as Meares celebrated before the line by punching the air.
It ended hopes of a fairytale conclusion to Pendleton's sensational career and saw Meares take revenge for Beijing.
China's Guo Shuang won bronze with a 2-0 defeat of Kristina Vogel of Germany.