As well as securing a supremely important win over Sir Alex Ferguson’s United, Vincent Kompany’s header in first-half stoppage time in April 2012 also put the prospect of a first-ever Premier League crown tantalisingly within City’s grasp.
Reflecting back on the 10th anniversary of our 2011/12 title triumph in his extended 93:20 CITY+ interview, the former City boss highlighted the special significance of that memorable Monday night derby at the Etihad.
And he said the symbolism of overcoming the reigning champions in such a huge game and suddenly being in charge of our title destiny (after being eight points adrift at one stage) was seismic.
“We were on top after many weeks and in that moment, we had everything in our hands,” Mancini recalled.
“After we beat them at the Etihad, we had a big chance to win (the title).
“We celebrated after the United game as is normal, but we also knew that ‘OK guys we have other difficult games. We need to have important concentration as it’s very important’.
“I have a lot of respect for Sir Alex and for what he did in football history in Manchester, and what he did with United.
“But you know when we played this game, we were both so nervous in that moment.
“I also think maybe in that moment something changed in Manchester after so many years.”
Kompany’s match-winning header that night stamped itself in the pantheon of all-time iconic City goals.
The captain and leader of Mancini’s squad, Kompany also cemented his reputation for being one of the game’s great central defenders during the Italian's time at the Etihad.
Ironically, in the initial early stages of his City career following his move to the Etihad from Hamburg in the summer of 2008, the Belgian had often been deployed as a defensive midfielder.
But Mancini revealed that he had no doubts that central defence was the role where Kompany’s talent would truly thrive.
And the Italian, who is now in charge of Italy's national side, said the influence and impact of our Belgian centre-half on that supremely talented City squad was almost impossible to quantify.
“When I arrived at City in 2009, Vincent played sometimes like a midfielder and sometimes on the bench,” Mancini recalled.
“But I knew Vincent from many years before as I followed him when he was a young player.
“I always thought he was a fantastic defender and for us he was a very important player and a very important man in the dressing room.
“And also, he scored that important goal against United!
“With his quality he could also play as a midfielder but we had many in that position.
“And I thought that Vincent was a really good central defender. I think one of the best probably.”