Michael Carrick enjoyed the perfect start to his second spell as Manchester United caretaker boss as second-half goals from Bryan Mbeumo and Patrick Dorgu inflicted massive damage on Manchester City's Premier League title hopes.

After so much recent discontent, this was a day when Old Trafford came alive, leaving Sir Alex Ferguson celebrating in the stands and United fans sarcastically waving off City spearhead Erling Haaland when he was replaced 10 minutes from time.

City had goalkeeper Gianluigi Donnarumma to thank for keeping his side in the game, with the Italian making a string of superb saves to deny Dorgu, Amad Diallo, Casemiro and Mbeumo.

But even Donnarumma was powerless to prevent United going in front as skipper Bruno Fernandes led a surging counter-attack and fed Mbeumo to his left before the Cameroon forward, returning from Africa Cup of Nations duty, applied the finish.

Eleven minutes later, United doubled their lead as City defender Rico Lewis was caught flat-footed, allowing Dorgu to nip in front of him and turn home Matheus Cunha's cut-back.

United had three goals disallowed for offside and Diallo hit the post late on but with Haaland extending his run to one goal in seven games, City didn't look like mounting a comeback.

As United's fans paid homage to Carrick, City boss Pep Guardiola slumped in his dug-out as his side's run without a Premier League win extended to four games, opening the door for Arsenal to strengthen their grip on the title.

However briefly, United move up to fourth, something they failed to do so often under Ruben Amorim, leaving Carrick to celebrate with his new coaching team at the end.

If there was one controversial moment for Manchester United to survive, it was Diogo Dalot's high challenge on Jeremy Doku in the opening minutes.

Many felt it warranted a red card but thankfully for Carrick, referee Anthony Taylor and fourth official Craig Pawson came to a different conclusion.

Once they had overcome that hurdle though, Carrick's team delivered the kind of statement performance the home supporters had waited so long for.

From back to front, United were magnificent.

In delivering only their third clean sheet of the season, United were indebted to Harry Maguire and Lisandro Martinez for neutralising Haaland's threat.

On the one occasion the Norwegian did look like scoring, Martinez slid in to block.

Behind them, goalkeeper Senne Lammens redeemed himself on the one occasion he made a serious mistake, turning away a goal-bound Max Alleyne header from a corner the Belgian had needlessly given away.

Kobbie Mainoo, so often overlooked by Amorim, flourished alongside Casemiro in midfield as United controlled the game.

By the end, United's fans were singing their song to Michael Carrick. After two wins and a draw in his first spell as interim boss in 2021, he has now added another memorable success to his list of achievements and long after the final whistle, he finally headed to the dressing rooms to huge applause.

City's title hopes have been left in tatters after being outfought and outmanoeuvred by their closest geographical rivals at a fervent Old Trafford.

United's supporters, players and staff were up for the challenge long before the first whistle and City were unable to match that intensity.

And, with Arsenal visiting Nottingham Forest later on Saturday, Guardiola's men could end the day nine points behind the league leaders with 16 games remaining.

The cacophony of noise and United's front-foot start performance unsettled City throughout, though captain Bernardo Silva should have done better with his first-half opportunity when he headed over from 10 yards out.

Academy product Alleyne could have made himself a derby-day hero but saw his looping header pushed away at full stretch by Lammens, while new signing Antoine Semenyo, who scored here for Bournemouth in the chaotic 4-4 draw last month, dragged wide from the edge of the box.

Despite Donnarumma's earlier heroics he conceded twice in the second half and it allowed legendary former Red Devils manager Ferguson to celebrate the result with a huge smile and cheer.

The full-time whistle put City out of their misery but left the deflated visiting players looking on in disbelief in the knowledge that the title is slipping away from their grasp.

Manchester United are next in action against Arsenal at the Emirates Stadium on Sunday, 25 January (16:30 GMT). Manchester City's next game is in the Champions League in Norway, against Bodø / Glimt on Tuesday, 20 January (17:45 GMT). Their next Premier League game is at home to Wolves on Saturday, 24 January (15:00 GMT).