Chelsea lost 2-1 away at Porto, a result made worse by the officials failing to spot what appeared to be a blatant penalty in the closing minutes.
As Diego Costa, a player renowned for his strong sense of fair play, tried to beat a defender, the ball struck the Porto man's arm.
Although right in front of the official standing behind the goal, the penalty appeals were ignored and play continued - depriving the English champions of a golden chance to earn a valuable point.
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