Sergio Aguero fired Pep Guardiola's into the lead on the 18th-minute mark after David Silva stole the ball from the Schalke defence and slid the Argentine through on goal.
Despite the early goal for City, it was Schalke who went into half-time in the lead of the game.
Nabil Bentaleb slotted the ball past Ederson twice from the penalty spot; Nicolas Otamendi handling the ball inside the area just after the half-hour mark followed by Fernandinho pulling down Salif Sane.
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Things went from bad to worse after the break as we were forced to play the final 20 minutes of the game with just 10 men, Otamendi being sent off for a second bookable offence.
However, an incredible final five minutes saw City turn what looked to be game-over completely on its' head.
View all the best pictures from City's dramatic victory via the gallery below!