So "Il Postino" has delivered. Manuel Neuer had sunk to his haunches, his left arm still aloft as if signalling the surrender, as Mario Balotelli ripped off his shirt, flung it to the turf and flexed his muscles. Claudio Marchisio's embrace rocked through the forward but by the time the rest of the delirious Azzurri descended upon him, the adrenaline-fuelled snarl was melting into a broad smile. One myth has at least been dispelled: the striker is more than happy to celebrate a goal, and particularly one this special.

The crunched explosion of a finish from Balotelli's right boot, dispatched so ferociously beyond a startled Neuer nine minutes from the interval, felt pivotal. A sign that a player who can infuriate as much as he dazzles can flourish at this level. It was a goal to sum up the 21-year-old, his gathering of Riccardo Montolivo's punt hinting initially at clumsiness before a cuter touch set up the finish. Against another opponent the goalkeeper might have been confident of his angles, and the retreating Philipp Lahm capable of recovering to intercept, but the brute in Balotelli would not allow it. Italy had been defending a corner five seconds earlier. Now they were on the verge of a ninth major final.

The nickname that is likely now to catch on requires a fuller explanation. On the eve of this contest, Twitter had been awash with a quote attributed to Balotelli who had apparently been asked why he refused to celebrate his goals. The riposte snapped back: "When I score, I don't celebrate because I'm only doing my job. When a postman delivers letters, does he celebrate?"

Yet there are exceptions, and a European Championship semi-final against Germany demanded emotion. The Manchester City striker had attempted a more matter-of-fact strut as he departed at the interval – his was an air of "so what's all the fuss about" as the cameras focused in – but the substitute Alessandro Diamanti, with a hug and a mouthed "wow" by the tunnel, betrayed what the watching world was thinking. To have witnessed a goalkeeper of Neuer's class so helpless said it all.

Poland clearly suits Balotelli. He has scored all of his international goals here, from the winner in a friendly in Wroclaw back in November 2011, to his team's second against Ireland in Poznan this month. He now has four in 13 games. This contest had initially passed him by, the forward too isolated while Germany poured through. As the midway point of the half approached and Italy started to make inroads of their own, Andrea Pirlo sprayed a glorious pass for Giorgio Chiellini to collect, with the full-back finding Antonio Cassano. The Milan striker's turn away from Jérôme Boateng and Mats Hummels, one of the most lauded defenders at these finals, left the Germans splayed.

The cross was delicious, bypassing the panicked Holger Badstuber, for Balotelli to thump a free header back and beyond the disorientated Neuer. His reaction had been more ecstatic then, flapping his shirt as he charged after Cassano – Hummels' tormentor-in-chief through the 58 minutes he managed – and embracing his strike partner. That pairing, enigmatic yet potentially destructive, might yet prove key to claiming this tournament. On the occasions they click, they seem irrepressible. Spain may look impregnable, but they will be wary.

Yet the reality is no one, least of all Cesare Prandelli, can predict the impact Balotelli will have at the Olympic Stadium. The manager had mouthed a warning to his matchwinner to keep his cool having been booked for removing his shirt, a reminder that his game is always played on the brink. Even on the biggest occasions he is a player capable of the sublime to the utterly ridiculous, with memories still fresh of his indiscipline at the Emirates in April when City appeared to have surrendered the title. Even at these finals, He had only summoned his best previous display after starting sulkily on the bench against Ireland, and had missed too many chances against England for comfort. If Italy were guilty of profligacy that night, the striker was the main culprit.

Yet to witness his trampling of Badstuber, Hummels et al was to wonder why there had been cries for his omission. In the aftermath of the penalty success against Roy Hodgson's side, Prandelli had fielded questions over his faith in the former Internazionale forward. His relationship with Italy's media, as demonstrated by the wildly inappropriate cartoon that appeared in Gazzetta dello Sport this week, is fractious at best. Even his team-mates have found him difficult at times, Daniele De Rossi admitting on the eve of this game that he had "shouted at him at half-time" of the England game in Kiev to rouse him from his lethargy.

"But how do you try to work out what goes on in the head of such a young man?" asked Prandelli. "In terms of his behaviour, mentality and psychology, he has changed radically with us." He will be more loved back home after this display, and with a final flourish maybe still to come. His evening ended with a kiss for his adoptive mother, Silvia, in the crowd. This felt like a coming of age with the Azzurri. Germany suffered his arrival.