Manchester United struck twice in the closing minutes to stun Manchester City in a dramatic derby conclusion at Etihad Stadium.

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.

United's late win was something few – perhaps not even Amorim himself – saw coming as a game that had been so undistinguished appeared to be moving towards an uneventful conclusion.

And then, in a final few minutes totally out of keeping with the mediocre fare that had gone before, United gave Amorim a personal triumph that will instantly increase his standing among United's supporters.

United had barely been troubled by Pep Guardiola's off-colour Premier League champions, but had created little of the their own, that Fernandes chance apart, until the always lively Diallo took a hand.

He collected a poor pass from Nunes in the 88th minute, who then compounded his error by chasing back and flattening the United forward with a reckless challenge, allowing Fernandes to make up for his earlier miss.

Diallo then showed real composure in the final minute of normal time to squeeze in United's winner from a title angle, Etihad Stadium stunned into silence apart from the ecstatic visiting fans.

Amorim took two big decisions to ditch Rashford and Garnacho from his squad completely, an early indicator that he will not shy away from difficult calls, no matter how big the profile of the player involved.

It had the desired impact, albeit late on, as United returned to winning ways in the most satisfying way possible after losing at Arsenal then at home to Nottingham Forest.

City continued their retreat into the dark shadows of their old glories as they snatched defeat from the brink of victory in the Manchester derby.

As he has in recent times, Guardiola cut an agitated, animated figure, even almost expressing his displeasure when City's goal from Gvardiol's header came after Kevin De Bruyne's header had been deflected in the direction of the defender.

Guardiola was grateful for that advantage as the clock ticked down, only for City to engineer another damaging result with a late collapse as United sensed vulnerability in a side that has completely lost the aura of superiority that sustained them as they won an historic four straight Premier League titles.

City barely created any meaningful opportunities, Erling Haaland marginalised, the midfield lacking creation and captain Kyle Walker embarrassing himself when he needlessly collapsed to the floor in dramatic fashion in a tame head-to-head with United striker Rasmus Hojlund.

These are troubled times for City, as they trail league leaders Liverpool by nine points having played a game more, and are currently struggling to keep their Champions League campaign afloat.

This is alien territory for Guardiola – and on their evidence there will be no quick fix to navigate a route out of the current crisis.