Liverpool - 2005
Liverpool were down and out in the 2005 Champions League final in Istanbul. They trailed 3-0 at half time to AC Milan in what was looking likely to be a rout.
From somewhere however the Reds found some inspiration. They scored three goals in six second-half minutes forcing the game into extra time and eventually to penalties.
Jerzy Dudek's heroics helped Liverpool to victory and the most unlikely of their five European triumphs. Having looked defeated at half time this must mark as one of the greatest comebacks in football.