Manchester City's fantastic recent record in derbies against bitter rivals United was emphatically halted on 12 April, with manager Manuel Pellegrini's side slumping to a miserable 4-2 defeat despite having led early on through Sergio Aguero.
The loss was City's sixth in their last eight Premier League fixtures and a fourth consecutive defeat away from home, hardly form befitting of a team looking to retain a title they have won twice since 2012.
Quite simply, the club is rapidly approaching a crossroads. They are lying in fourth place with an ageing squad who have failed quite dismally in their attempts to resist the challenge of Chelsea domestically and once again exited the Champions League before the quarter-final stage.
The coming summer at the Eithad Stadium will be critically important if City are to remain as contenders and not run the considerable risk of being left behind by Jose Mourinho's side as well as rejuvenated Arsenal and Manchester United.
Here, IBTimes UK assesses the state of the current City squad, stating who should be kept as well as which players should be moved on as part of an overdue rebuild. We will also speculate on the future of Pellegrini, assessing who could replace the Chilean as the pressure mounts following yet another lacklustre performance.
Who should stay?
Sergio Aguero – Perhaps an obvious but nevertheless salient point, City must look to retain the services of Aguero as a matter of upmost importance moving forward.
With 17 goals and six assists in 27 top-flight games so far this season, as well as six strikes in Europe, the nimble Argentine, 26, remains the club's most important asset and his ability to terrify defenders with his pace and footwork will not be easy to replace.
Real Madrid have been frequently linked with Aguero as a possible replacement for Karim Benzema in the recent past despite his previous ties to rivals Atletico but any summer interest should and will be rebuffed.
David Silva – Like Aguero, the affable Silva's ingenuity and composure in the final third makes him simply indispensable to City.
On the all too rare occasions that the team have performed at their best this season, most of what is good about their attacking play has tended to run through the versatile midfielder, who also possesses a keen eye for a pass.
At 29, Silva, who signed an improved five-year contract in August 2014, obviously contributes to City's age issue but it would be more than a little foolish to suggest that he is already beyond his peak.
Vincent Kompany – A slightly controversial choice given his chronic lack of form this season but the Belgian centre-back, previously the best in the Premier League before an alarming drop in standards following persistent hamstring trouble, is still an influential figure who should not simply be coldly consigned to the scrapheap.
If he can prove his fitness over the longer term, captain Kompany, 29, still has a prominent role to play for City as they look to rebuild and has surely earned a stay of execution with his previously stellar performances since arriving from Hamburg during the reign of Mark Hughes.
At 34, Martin Demichelis, who has improved following an initial stuggle to adapt to the pace of English football, is approaching the end of his career and £32m signing Eliaquim Mangala, 24, has done preciously little during the early stages of his Premier League career to suggest that he can be Kompany's long-term successor.
If they can find him a reliable and capable partner, then it is not beyond the realms of possibility that Kompany could recover from his recent slump and go on to relive past glories.
Others to stay: Joe Hart, Wilfried Bony, Martin Demichelis, Fernandinho, James Milner
Who should go?
Yaya Toure - The formerly dominant Ivorian has been heavily criticised during City's recent slump but only the most ardent supporter would argue much of that condemnation has not been merited.
He just simply no longer seems as effective and, as was perfectly highlighted by the likes of Gary Neville in the aftermath of the capitulation at Old Trafford, a seeming reluctance to fulfil any defensive duties often renders him a liability when City are not in possession and playing with only one of Fernando/Fernandinho alongside him in midfield.
If the 31-year-old stays 100% committed to the cause, Toure is certainly still good enough to play a prominent role for City in his preferred position.
However, in light of recent displays and with the rumblings of discontent that led many to believe he was angling for a move away despite having two years left to run on his current deal still fresh in the memory, it looks likely he will depart with former manager Roberto Mancini apparently keen to take him to Inter Milan.
Edin Dzeko – A competent if limited secondary striker, Dzeko has scored some important goals for City during his four years in the Premier League yet has always appeared disgruntled at a lack of regular playing time.
Indeed, the 29-year-old has made only 12 top-flight starts this season, scoring just four goals. Such a lack of impact from the Bosnian and fellow forward Stevan Jovetic led to Pellegrini lavishing £28m to secure the signing of Wilfried Bony from Swansea in January.
That deal, coupled with Dzeko's understandable desire to feature more frequently and the expectation that City will seek to further bolster their strikeforce during the next transfer window, would strongly hint that an exit is forthcoming.
A return to the Bundesliga, where won the title with Wolfsburg in 2009, seems the most likely option.
Jesus Navas – Of all City's dubious signings made during recent windows, Navas has arguably been one of the most frustrating.
It is patently obvious that the Spaniard, a World-Cup winner in 2010, has pace in abundance, yet he never quite seems to perform to the best of his ability and it hard to ignore the nagging feeling that he would perhaps find it easier to progress his career elsewhere.
Frankly, it said it all when the 29-year-old raced through on goal just minutes into the derby at Old Trafford yet could only fire a disappointingly tame effort straight at the legs of United 'keeper David de Gea.
His end product has just not been good enough and will need to improve drastically on a consistent basis if he is to avoid the inevitable cull.
Others to go: Fernando, Stevan Jovetic, Aleksandar Kolarov, Gael Clichy
Who should they sign?
Paul Pogba – With Financial Fair Play restrictions that landed the club a hefty fine and limited them to a spend of no more than £49m set to ease considerably this summer, City will be largely free to throw money at their problems like an overzealous toddler hurling confetti at a wedding.
Top of their transfer shortlist will likely be talented Juventus midfielder Pogba, 22, who has established himself as arguably the most promising young player in Europe following his exit from Manchester United in 2011.
Hugely gifted, skilful and likely to be permitted to leave Turin in the event that the reigning Serie A champions' hefty valuation is met, capturing a player of Pogba's skill and limitless potential would be an ideal tonic for City and would no doubt ease the pressure on the likes of Ferran Soriano and Txiki Begiristain.
If Juventus CEO Giuseppe Marotta is to be believed, it could take up to an incredible €80m to land Pogba, but it could be a price well worth paying.
Ross Barkley – The England playmaker has seen his progress stunt a little this season in the midst of a disheartening campaign at Goodison Park that saw Everton concerned by the very real threat of relegation before embarking on a four-match unbeaten run, yet he remains an attractive option nonetheless.
The £50m figure that has been previously quoted for his signature is obviously too high and City will be hoping a series of rather indifferent performances will help knock that price down. At 21, Barkley has ample time to improve and the impact of the Toffees' fortunes on his individual form should not be underestimated.
Having seen the likes of Jack Rodwell, Adam Johnson and Scott Sinclair fail to live up to expectations after following a similar path, it could be that City will resist the temptation to repeat those mistakes again and continue to look abroad for better value.
However, Barkley seems an altogether more resilient character who could thrive alongside the likes of Silva and Aguero given the necessary time to adapt.
Aaron Cresswell – The left-back has been remarkably consistent for West Ham in recent months and is probably deserving of the "bargain of the season" moniker - not to mention an improved contract - following a summer move from Ipswich for an initial fee believed to be in the region of £3.75m.
The 25-year-old could perhaps do with another season of similar consistency before considering a move of this stature. But City could feasibly be tempted to swoop early with Kolarov likely to depart, Clichy clearly not up to the required standard and Chelsea rumoured to be tracking Cresswell as a potential replacement for Filipe Luis in order to boost their quota of homegrown players.
Marco Reus – Names like Pogba and Reus may sound like farfetched signings at first, given their stature and importance to their respective clubs, but these are the calibre of players City need to be targeting if they are to swiftly restore credibility.
Like the Frenchman, Reus, 25, has struggled with injury of late yet his ability is certainly not in doubt. Capable of playing anywhere across the frontline or indeed out on the flank, his versatility cannot be ignored but City would likely face staunch competition from a number of European heavyweights in any transfer pursuit.
Potential Pellegrini replacements
While City's underperforming stars should undoubtedly bear the brunt of the criticism aimed at the club in its current malaise, it is impossible to absolve Pellegrini of all blame.
Despite his refreshingly calm persona, one that often provides a welcome alternative to the likes of the relentlessly controversial Jose Mourinho, the former Villarreal and Malaga boss is likely to lose his job at the end of the current campaign having been unable to halt such an alarming slide.
But who could be replace him?
Carlo Ancelotti – Many bookmakers' favourite for the job in the event that Pellegrini is sacked. Ancelotti still has a year left at Real Madrid, yet a failure to win La Liga for a second season in succession will likely hasten his exit regardless of the fact he succeeded in ending the club's long wait for a 10th European Cup at the first time of asking.
He has tasted success in the Premier League before, of course, winning the double with Chelsea in 2010 before being sacked the following year courtesy of a struggle not too dissimilar to the one currently endured by Pellegrini.
Diego Simeone – Simeone has attracted much praise for his sterling work at Atletico Madrid, with whom he won the 2013-14 La Liga title against the odds and also progressed to the final of the Champions League.
Unlike rival Ancelotti, though, he appears to have strong job security in Spain and showed his feeling for the club only last month by signing a new deal until 2020.
Pep Guardiola – No doubt City's ideal candidate, yet he will probably see the opportunity as having arisen too early after just two seasons at Bayern Munich.
He left Barcelona in pursuit of a new challenge, so could he be persuaded to do the same again given that he is on the verge of winning a second consecutive Bundesliga crown at a canter?
Jurgen Klopp – The fiercely loyal German is universally adored at Borussia Dortmund and under contract until 2018. However, the club's surprising struggles this term could lead to him deciding to start afresh sooner than he had previously intended.
Klopp has been widely earmarked as an eventual successor to Arsene Wenger at Arsenal, yet his clear philosophy and vision could help revolutionise City and his popularity among players would prove useful in controlling a squad not short of big egos.
Patrick Vieira – An unlikely option given his lack of managerial experience but the former City midfielder looks to have impressed with his work in the youth setup despite the lack of an obvious pathway for youngsters through to the first team. An intriguing outsider, for sure.