A brace from Angelino strike marked a superb second-half display, which saw the hosts come from behind to claim the victory.
United had led through Ashley Fletcher’s 43rd-minute effort but - inspired by their half-time team-talk and the in-form Iheanacho - City were rampant, as they had been in the midweek triumph over Southampton.
Patrick Vieira’s side headed into the game on the back of that 4-0 win and desperate for a slice of revenge for the comprehensive defeat to the Reds earlier this month.
Vieira opted to make just two changes from Tuesday’s side, with Jose Angel Pozo and Pablo Maffeo coming in to replace Aaron Nemane and James Horsfield.
With the visitors having already been crowned champions, there was realistically little to play for in this encounter other than local pride and the hope of ending the campaign on a high – not that anyone told these two sides.
In a first half packed with crunching tackles, it was clear just how much this fixture meant to the players, as George Evans had told mcfc.co.uk.
Before the game, the hosts gave their visitors a customary Guard of Honour – but that was the first and last we saw of the pleasantries.
It was United who started the brighter, creating the first chance of the afternoon when Tom Thorpe headed over a corner at the back post.
Full of confidence, the visitors looked sharper in the opening exchanges but City responded well to the early threat and almost took the lead themselves as Olivier Ntcham fired an effort goalward, which was deflected just wide.
From the resulting corner, George Glendon tried his luck but his curling shot lacked the power to really trouble Kieran O’hara.
From then on, it was a fairly even contest but neither side were able to sustain a lengthy period of possession.
Cameron Humphreys did well to snuff out a Reds attack as Joe Rothwell looked to be clean through, before Fletcher blazed over from a tight angle.
Iheanacho then looked certain to open the scoring when the ball ricocheted into his path – but having stayed on his feet when the goalkeeper seemed to obstruct his route to goal, the chance went begging.
The striker then drilled straight at O’hara and the Blues were punished for their lack of penetration with two minutes of the half remaining, as Andrew Kellett skipped past Jack Byrne’s challenge before squaring for Fletcher to tap home from close range and give the Reds a half-time lead.
It was a blow somewhat against the run of play but buoyed by the words of their boss, the hosts were much more direct in the second period. A series of dangerous crosses caused havoc before a piece of individual brilliance levelled the score on 55 minutes.
It was Iheanacho who earned it, expertly turning his man in the centre before coolly slotting into the bottom corner. It was a goal of technique, skill and composure – just what the Blues had lacked in the opening 45.
Sensing blood and with the momentum behind them, the home side almost turned the game on its head within minutes. Brandon Barker curled a long-range effort just wide before Byrne headed over the bar, with City growing in confidence.
Seeking his and City’s second of the contest, Iheanacho then stung the hands of O’hara with a low effort which was pushed wide.
From that set-piece, City did take the lead. A well-worked move released Angelino in space and the left-back’s curled effort deflected into the back of the net.
Having surrendered their advantage, the Reds did little to try and regain it. Callum Gribbin saw an effort fly well over the bar before the Blues put the game to bed ten minutes before the end.
Either Ntcham or Iheanacho could have netted it, as they both chased a loose ball in a dangerous area – but it was the latter who took responsibility, curling a beautiful effort into the bottom corner to effectively seal the contest.
Barker almost put the icing on the proverbial cake with a trademark solo run and shot but O’hara was equal to it to ensure his side’s margin of defeat ended with just the two goals.
So ended the International Premier League Cup winners’ campaign, with a derby win sparked by some fine football and local pride restored.
