It is the morning of 19 December 2009. When Mark Hughes switches his phone on he fields a series of calls from friends and reporters telling him he is about to be sacked by Manchester City.

At his local newsagents this prediction is already emblazoned in headline form across the backpage of a tabloid but, when Hughes seeks clarification from City, none seems forthcoming. Ominously the previously supportive press officer is said to be "away on a trip" and, by now, the radio airwaves are crackling with speculation that Roberto Mancini is the club's new manager in waiting.

It is a Saturday and in a matter of hours City are kicking off at home against Sunderland. Hughes and his staff debate what to do. With the silence from the boardroom still deafening they prepare the players as normal, take their seats in the dugout and oversee a 4-3 win over Steve Bruce's side. Within minutes of the final whistle Hughes is told to clear his desk while Mancini prepares to be publicly anointed as his successor.

During the past few years City have done a lot of things extremely well, notably some life‑changing charity work locally and worldwide, but they handled Hughes's departure appallingly.

The fear now at the Etihad Stadium is that this crass behaviour could come back and bite them. On Sunday Mancini's team need to beat Hughes's Queens Park Rangers at Eastlands to be sure of winning the title. Should City stumble, the notion that it might be karma in action will prove impossible to resist.

"There's a big irony in that it's him we're up against," says Joleon Lescott, one of several City first‑teamers who were either signed by the legendary Manchester United striker or worked under him. "Mark Hughes was a great boss and he was very good to me."

If the knowledge that Hughes inspired extraordinary loyalty from many City players, Carlos Tevez foremost among them, will be irrelevant on Sunday, the reality that QPR require a point to be certain of avoiding relegation is making everyone at the Etihad distinctly queasy.

By way of added spice not only does Hughes's backroom team contain former City employees including Mark Bowen, Eddie Niedzwiecki and Kevin Hitchcock but the team features three Eastlands old boys, Nedum Onuoha, Shaun Wright‑Phillips and Joey Barton.

It has not been forgotten that the former City chief executive Garry Cook resigned in the wake of claims that he had emailed Onuoha's cancer‑suffering mother, mocking her illness. Or that an investigation by City pronounced there was "foundation" to the accusations.

While Onuoha left for QPR in January Barton departed in the summer of 2007 – a year before Hughes succeeded Sven-Goran Eriksson – in the wake of a training‑ground assault on a team‑mate, Ousmane Dabo, to which he later pleaded guilty in court, thereby incurring a suspended prison sentence plus community service.

Potential sub-plots abound but the principal human-interest storyline promises to be in and around the adjacent technical areas.

Understandably Mancini took a dim view of ill-judged – if not entirely inaccurate – comments from Hughes last autumn in which he described the Italian as "autocratic" and blamed him for Tevez's three‑month disappearance to Argentina.

"Maybe it's a little bit fated that I'm going back to City on the final day," says Hughes. "If we were to get something, it would be a fantastic story. They're going for the title, we're trying to stay in the league. That fixture loomed quite ominously in the distant future when I first took over here [in January]. But maybe now the stars have aligned and things have fallen on our side of the line."

Mancini, whose side have not lost at home all season, will be mindful that Hughes and his staff possess rare, possibly invaluable, knowledge of various City players' little-known technical flaws, tactical weaknesses, preferred tricks and on-pitch foibles. He is also conscious that his Welsh counterpart continues to feel deeply wronged by his dismissal after only 18 months in charge and at a time when City were sixth in the Premier League and had lost only twice since the start of the 2009‑10 season.

"I had all the pain and now other people are getting the gain," Hughes has complained repeatedly. The 48-year-old's mood is hardly enhanced by his managerial career, which had begun promisingly with Wales and then Blackburn Rovers, suddenly striking a few walls. There was a decent season at Fulham followed by a resignation designed to "further my ambitions" but which instead merely saw him ignored by Aston Villa and lose out to Martin O'Neill for the Sunderland job.

Eventually he accepted QPR's offer but the feeling persists, at least for anyone who monitored the laudable transformation he implemented at Blackburn, that Hughes belongs at a bigger club.

The worry is that a man who commands immense affection from not only former players – Craig Bellamy, Shay Given, Tevez and Robbie Savage are just a few of those who will not hear a word said against him – but, equally significantly, a cross-section of junior employees at his former clubs was spoilt by the six‑star luxury he swiftly grew accustomed to with City. Reports of Hughes's demands for bigger and better desks, chairs and computers in an ultimately expanded office at Fulham certainly did not reflect well on a man who did himself few favours with that "autocrat" jibe about Mancini.

At least Sir Alex Ferguson probably enjoyed it. There were a few years when Hughes and his old United manager experienced frosty relations but since the latter's City exit the ice has broken, with Ferguson remembering precisely why he once described the younger, then surprisingly shy, young Welshman as a "warrior you'd trust with your life".

Now he has no option but to pin his title hopes on one of Old Trafford's great centre‑forwards and to pray that QPR's players can somehow replicate their manager's old brand of brilliance and brutality. "I just wish Sparky was still playing," says Ferguson. "But Mark was sacked in a very unethical way and he'll remember that."