Belgium, the No.1 ranked team in the world, had no answer to their opponents’ pace, energy and ebullience, Mancini’s men having ripped up the caricature of Italy as defensive-minded suppressors of games.
For Mancini, victory afforded him revenge over Belgium coach Roberto Martinez, for Manchester City’s defeat to Wigan in the 2013 FA Cup final.
That defeat saw Mancini sacked by City three days later, but the 56-year-old has underlined his coaching prowess at this tournament, steering Italy from failure to qualify for the 2018 World Cup to the last four of the Euros.
For Belgium’s famed Golden Generation, led by Kevin De Bruyne and Romelu Lukaku, it was another bitterly disappointing failure at a major tournament, Martinez’s side ultimately coming up short when it mattered once again.
Italy made two changes from the side which overcame Austria in extra-time, skipper Giorgio Chiellini returning after injury, while Federico Chiesa’s goal in that game, after coming off the bench, earned him a start.
Belgium had fitness concerns over De Bruyne and skipper Eden Hazard, the former starting but the latter not even making the bench, replaced by Jeremy Doku.
Given the standing and quality of both sides, this could have justifiably been the final, Belgium boss Roberto Martinez bemoaning on the eve of the game that such a big clash came at the quarter-final stage.
Both sides took maximum points from the group stage, and with both teams having won their last 14 European Championship matches, a run shared with Germany, the winners here would set a new competition record.
Italy went into the game on the back of a new international record of 31 games unbeaten, while Belgium had lost just once in their last 27 matches.
It was Italy who struck first, in the 13 th minute, Chiellini turning the ball in from a free-kick Belgium failed to clear, but Martinez’s side received a reprieve when the goal was ruled out for offside.
That let-off seemed to galvanise Belgium, who put Italy under a sustained spell of pressure, yielding three corners inside the first 15 minutes.
De Bruyne served notice of his enduring threat in the 22 nd minute, bursting forward and forcing a fine save at full stretch from Gianlugi Donnarumma.
The Manchester City playmaker was the architect three minutes later, funnelling the ball to Romelu Lukaku, Donnarumma again repelling the threat.
But it was Italy who took the lead in the 31 st minute, sloppy Belgium defending punished by Nicolo Barella, who stayed on his feet under pressure before scoring with a clinical shot across Thibaut Courtois.
Mancini’s men duly made it 2-0 two minutes later, Insigne cutting inside and skipping past Youri Tielemans before sending a majestic, curling strike beyond the despairing reach of Courtois.
Belgium were handed a lifeline a minute later, when Jeremy Doku was fouled by Giovanni Di Lorenzo, Lukaku converting from the penalty spot his 64 th goal from 98 caps – to drag the Red Devils back into the game.
Lukaku should have made it 2-2 just after the hour when De Bruyne squared the ball to him inside the six-yard box, but he could only find the post, under pressure from Leonardo Spinazzola.