Josko Gvardiol's first-half header looked to be giving City victory in a largely dismal clash until United staged a remarkable turnaround to give new manager Ruben Amorim a landmark win early in his reign.
Amad Diallo was United's star performer, winning the 88th minute penalty that saw Bruno Fernandes equalise after the youngster was fouled by Matheus Nunes.
As City tried to regroup, Diallo then pounced in the closing seconds of normal time to score from a tight angle.
It was a rich reward for United boss Amorim after he ruthlessly axed Marcus Rashford and Alejandro Garnacho from his match day squad, but then suffered an early blow when Mason Mount was struck down by his latest injury, limping off after only 14 minutes.
Opportunities were at a premium in a game largely made up of desperate mediocrity, United looking to have wasted their best opportunity to equalise 17 minutes from time when Fernandes raced clear on to Rasmus Hojlund's pass, only to lift his finish over the onrushing Ederson but wide.
The game was turned on its head in that frantic finale, City's fans furious and jeering their side while United's followers celebrated wildly in their corner of Etihad Stadium....<<<Read More>>>...