New signing Sergio Aguero watched from the stands as Mario Balotelli opened the scoring one minute before half time with a powerful header, a fitting reward for what was a dominant City display orchestrated by the sublime talents of David Silva.
Edin Dzeko made it 2-0 moments after the restart, with Silva once more central, and Adam Johnson rounded off the victory with a third goal in injury time, after some good build up play from Shaun Wright-Phillips.
The victory ensured City finished top of the pile for the four-team tournament, after their 3-0 victory against an Irish Select XI on Saturday, but Mancini has his eyes on greater success.
Mancini dismissed the FA Cup trophy sitting beside him in the post-match press conference as 'the past', and played down the importance of the Dublin pre-season tournament as he looked toward next week's Charity Shield against Manchester United, which is the last warm-up before big-spending City start their assault on the Premier League and Champions League.
"It was not an important game, it was only important for us because we want to put 90 minutes in our legs for next week's game," he said.
"It is difficult to play two games in two days, but it was important mostly that we prepare well for next game.
"I was happy with how Mario Balotelli played and I think if Mario plays this season as he did this afternoon he can be an important player for us.
"Edin Dzeko can score a lot too, and Silva has everything, we know this."
Celtic had earlier beaten the Irish Select XI 5-0 in a match that proved a happy homecoming for two of the Scottish side's Irish contingent.
Republic of Ireland internationals Anthony Stokes and Daryl Murphy both scored in the first half, with Stokes grabbing a second after the break.
Gary Hooper bagged two for himself as Neil Lennon's side took advantage of a raft of substitutions by the home representatives.
Celtic had sent out a weakened side, compared to Saturday's team that lost 2-0 against Inter Milan, with only Stokes, Hooper and defender Daniel Majstorovic regulars in last season's team.
But that didn't affect them, and the victory gave some enthusiasm to Lennon, with their second Scottish Premier League game next weekend.
"It's been a very worthwhile weekend and that was a nice way to finish the tournament off," Lennon said.
"It was good to see the lads score some goals. I felt we deserved goals against Inter on Saturday.
"It was important we got some game-time into some of the lads too. There were aspects I'm not happy about but you can't be perfect."
Source: AFP
Source: AFP