Four wins in his opening four encounters, coupled with a nice line for the media and his photogenic appearance all combined to ensure the former Inter Milan boss was the hottest property in English football.
He walked into news conferences with a huge smile on his face and was full of confidence and joie de vivre.
How quickly things can change and how quickly Mancini is working out that the Premier League is a playground.
Since that bright beginning, City have started to deteriorate and deteriorate badly, culminating in their fifth round FA Cup replay exit to Stoke City on Wednesday.
They have now won just two of their last eight matches and the level of pressure on Mancini is already rising to a degree that he could not have anticipated when he arrived.
Fans were quick to air their views on radio phone-ins and website forums, berating the Italian for his negative approach while local newspapers report dressing room unrest caused by the players' reluctance to embrace his tough new training regime.
Mancini, though, has not been helped by circumstances at City. Since Sheikh Mansour bin Zayed al-Nahyan bought the ailing club in September 2008, City have had untold millions at their disposal and although that has enabled them to bring in the likes of Robinho, Emmanuel Adebayor and Carloz Tevez, it has also led to one factor that no manager can ever really control: expectation levels.
City's followers, and their new boardroomm have gone from merely hoping for a decent Cup run every year and to perhaps stealing a point here and there from the established members of the 'Big Four', to believing they have a rightful place among the footballing elite.
BAD FORTUNE
Hughes was sacked because he did not make that transformation quickly enough and Mancini could well go the same way if he does not get them winning again.
In his defence, Mancini has been cursed with bad luck in recent weeks. Adebayor was sent off against Stoke on Wednesday and has received a four-match ban for his troubles and Tevez has also been absent for the last four games because his daughter was born prematurely, prompting him to dash back to Argentina.
By the time Adebayor is back from his second violent conduct suspension of the season, City will have been without their two biggest threats in the same side for over six weeks, a factor that could deliver the final crushing blow to their ambitions of finishing in the top four.
It could also be the factor that aids and abets Mancini's departure.
He still wears the pristine blue and white fluffy scarf but the smile is now long gone. His shoulders droop when he walks into news conferences, his answers have become monosyllabic utterances and his demeanour speaks louder than his protestations that he is not going to get the sack.
"It's impossible that I'm under pressure," he told reporters on Friday. "In Italy it was different because Inter were a top squad and you must always win but I'm not under pressure. I played for 20 years as well but I'm not under pressure."
