THIS Sunday sees the latest episode of a Manchester soap opera as dramatic and long-running as Coronation Street. The players of City and United might be the prime actors but the starring roles undoubtedly belong to Jose Mourinho and Pep Guardiola, two characters with the kind of convoluted and criss-crossing backstories of which any aspiring script writer would be proud.

Their shared history began under Bobby Robson at Barcelona – when Guardiola was the veteran player and Mourinho the aspiring coach and translator.

While it might not astonish you to hear that this upstart, headstrong Portuguese had a habit of rubbing up his opponents the wrong way – there was an incendiary incident involving Athletic Bilbao coach Luis Fernandez - on more than one occasion he found Guardiola a kindred spirit prepared to fight his corner.

Legend has it that Mourinho retains a photo of him sharing an embrace with Guardiola after the club won the 1997 Cup Winners Cup final in Paris.

Such sweetness and light didn’t last long, however. Looking for a new job after his departure from Chelsea in 2007, Mourinho was interviewed for the top job at Barcelona a year later, even indicating that he would promote Guardiola from his post with the B team to have as assistant. Instead, Instead, Txiki Begiristain )now at City) opted for Guardiola himself. While it was a decision which laid the groundwork for a period of Catalan dominance, rejection is said to have ‘poisoned’ relationships with the Portuguese.

And who should come along with Inter Milan in the Spring of 2010 than Mourinho, masterminding a 10-man Italian outfit to seal a 3-2 aggregate victory in the Champions League semi-finals?

In his book, ‘I am Zlatan’, Zlatan Ibrahimovic, accused his former manager of ‘s****** himself in front of Mourinho’. “Mourinho is a big star,” he continues. “He’s the opposite of Guardiola. If Mourinho lights up a room, Guardiola draws the curtains.” For a long time, a life-size cardboard cut-out of himself at the moment of victory in the Camp Nou had pride of place in Mourinho’s managerial office.

That match also turned out to be a decent job interview, as Real Madrid – desperately seeking someone capable of getting under the skin of their biggest rivals – turned to Mourinho to transform their fortunes. So began a period of enmity between these two old friends which became known in the Spanish press as ‘the disease’, a period where Mourinho was thought only to refer to Barcelona by the name ellos (them).

While Guardiola had the better record in match-ups between the pair, Mourinho successfully wrested the La Liga title of 2011-12 in his second year in charge and matters between the respective coaching staffs came to a head with a mass melee involving Mourinho and Barca assistant Tito Villanova at a Copa del Rey final in 2011. Guardiola’s decision to take a sabbatical from the sport in 2012 has been at least partially attributed to the heightened nature of his rivalry with Mourinho’s Real Madrid, who he felt they were too physical and too keen to extend the rivalry beyond the field of play.

But surely all of that is water under the bridge now that the two men are near neighbours in Salford? Well, last season’s matches passed off without incident – Guardiola said that the two men ‘high five’ whenever they meet in the street - but both men have far more at stake this season, having failed to win the biggest prize in the English game in their maiden seasons. Sunday – with United without Paul Pogba and City perhaps minus David Silva - promises to be as much of a chess match as Bobby Fischer against Boris Spassky.

What makes their personal interplay so intriguing is their portrayal as polar opposites. The world knows Guardiola as the ultimate footballing idealist, while Mourinho is his alter ego, the sport’s arch pragmatist. “There are people, much more intelligent than me, who manage to sell an image of themselves, completely different to mine, but deep down they are the same,” Mourinho has said in the past of Guardiola. High fives or not, these two managerial masterminds will be desperate to get the upper hand on Sunday.