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.
Meares shed her visor in celebration before joining hands with Pendleton as the 2008 champion and reigning world champion paid tribute to the victor.
Pendleton was in tears as she removed her helmet and the visor which covered her face while the crowd chanted her name.
Mechanics and support staff were also tearful as Pendleton took a bow in the back straight to acknowledge the partisan support as her stellar career came to an end.
Pendleton told BBC1: "I'm just so relieved right now. I've been a bit overwhelmed with emotion.
"I would have loved to have won on my final race but I'm just so glad that's it all done and I can move on."