One of the most bizarre rows between clubs broke out this week after Porto took aim at Manchester City in a newsletter to their fans following their 0-0 draw with Pep Guardiola's men in midweek.
In a baffling 529-word rant, the Portuguese side slammed City players and Guardiola for their behaviour during the game while celebrating their qualification to the Champions League knockouts after finishing as runner ups behind them in Group C.
Their decision to take this dramatic step of public criticism has more than raised a few eyebrows, and has resulted in City hitting back after their surprising words.