The owners said the Italian's failure to meet any of his targets this season, with the exception of qualifying for the Champions League, had led to his dismissal.
The dramatic Sergio Agüero strike that won the title last May secured Mancini a lucrative five-year contract worth around £35m and a mandate to build City into an ongoing force. But 12 months on Mancini is unemployed, with the Abu Dhabi-led executive's decision to remove him coming after they allowed him to limp on when news broke on the eve of Saturday's FA Cup final with Wigan Athletic that they were in advanced discussions with Málaga's Manuel Pellegrini, who is almost certain to replace him.
Although on Monday morning Pellegrini denied he had reached an agreement with City, discussions between the club and his agent, Jesús Martínez, regarding financial terms and contractual clauses are at the stage where a deal is ready to be signed. This should now be a formality.
The Chilean is likely to start his new role at the turn of the month after City said the assistant manager Brian Kidd will "take interim responsibility for the remaining two games of the season and the post-season tour to the United States".
Until the announcement confirming Mancini's removal, posted on the club website at 10.22pm, City had not issued any public comment since indications began that the manager's job was in doubt. This had cast the Italian as an increasingly isolated figure, with it becoming a matter of when not if he would lose his job.
The statement said: "It is with regret that Manchester City football club announces that Roberto Mancini has been relieved of his duties as Manchester City manager. This has been a difficult decision for the owner, chairman and board to make and it is the outcome of a planned end-of-season review process that has been brought forward in light of recent speculation and out of respect for Roberto and his extensive contributions to the football club.
"Despite everyone's best efforts, the club has failed to achieve any of its stated targets this year, with the exception of qualification for next season's Uefa Champions League. This, combined with an identified need to develop a holistic approach to all aspects of football at the club, has meant that the decision has been taken to find a new manager for the 2013-14 season and beyond."
The reference to a "holistic approach" suggests a sea change in philosophy from top to bottom of the club, driven by the chief executive, Ferran Soriano, and Txiki Begiristain, the director of football. This may include playing 4-3-3 throughout the academy and in the first team. Following the removal of Mancini, who could be a divisive figure, there may also be a hope that the club will be more cohesive.
Khaldoon al-Mubarak, the chairman, said: "Roberto's record speaks for itself and he has the respect and gratitude of Sheikh Mansour [the owner], myself and the board for all of his hard work and commitment over the last three and a half years. He has clearly also secured the love and respect of our fans. He has done as he promised and delivered silverware and success, breaking the club's 35-year trophy drought [winning the 2011 Cup] and securing the title in 2012. I would like to personally and publicly thank him for his dedication to the progress that he has overseen and for his support and continued friendship."
Before the club's pursuit of Pellegrini emerged, the plan was for Mancini to end the season and have a review in the emirate. This would have been led by Mubarak and included Soriano and Begiristain.
Mubarak and his team were adamant that if it were decided to let Mancini go, there should be a candidate in place who had agreed terms and would be ready to take over. This was the strategy under which Pellegrini was approached.
With regard to Mancini's position being all but untenable before he was removed, City were in precisely the same position when he became manager in 2009. Then, it was common knowledge that he would supersede the incumbent, Mark Hughes as the Welshman took charge of the club's match with Sunderland on 19 December. Following a 4-3 win, Hughes was sacked.
City intend to make cuts lower down the club, too, with an extensive sacking programme. Soriano and Begiristain have decided the faults in the existing coaching staff go all the way to youth level and will make their point ruthlessly.
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