Alexis Sanchez was the hero for Arsenal with the Chilean star striking from close-range in extra-time to seal victory.
Sergio Aguero fired Manchester City into the lead just past the hour mark following deft assist from Yaya Toure.
Nacho Monreal finished from close-range to make it 1-1 with 20 minutes of the contest remaining.
With both side's tied at 1-1, extra-time was required but Sanchez struck from close-range in the 100th minute to seal a memorable win.
More to follow...