When Roy Hodgson was asked this week which player he would most like to pinch from a rival team at the coming World Cup finals, the England manager gave his questioner, Garry Richardson of Radio 5 Live, an answer that was both amusing and diplomatic. He would take Mario Balotelli from Italy for the opening Group D fixture, he said, followed by Luis Suárez from Uruguay, and then, for the final group match, "whoever is Costa Rica's best player – I haven't quite done my research on that yet".

His mention of Balotelli chimed with the general reaction to the news that England had been drawn to play Italy. Watch out, everyone said, for Super Mario on 14 June; the erstwhile enfant terrible of the Etihad will be back to haunt us. But if I were a betting man, it is not the former Manchester City striker on whom I'd be putting my money to inflict damage on Hodgson's team in the tropical heat of Manaus. It is a man who spent three years wearing the colours of the club on the other side of Manchester.

Apparently Sir Alex Ferguson felt that Giuseppe Rossi offered insufficient physical presence to prosper amid the hurly-burly of the Premier League. In his 26 years at Old Trafford, Ferguson achieved more than enough to be excused his share of mistakes, but the decision to let Rossi go is surely an error to rank alongside the selling of Paul Pogba, now emerging as a major force for Juventus and France, and perhaps that of Ravel Morrison.

The Italian public, and the people of Florence in particular, are in no doubt about Rossi's qualities and value. A man who made only five league appearances for United – and who rates not a single mention in Ferguson's latest volume of autobiography – is now established as the most potent striker in Serie A. Now 26, he is a potential star of next summer's tournament in Brazil: a Paolo Rossi or Toto Schillaci in waiting.

Rossi scores a lot of goals, and at Craven Cottage a few weeks ago, when Italy drew 2-2 with Nigeria in the most exhilaratingly competitive international friendly you could wish to see, he opened the scoring in the 12th minute. He took it beautifully, moving on to a neat pass from Balotelli and beating the goalkeeper, Austine Ejide, from close range with deft aplomb. It was his seventh goal in 29 appearances for the Azzurri.

He played just over 50 minutes of the match before Cesare Prandelli withdrew him and in that time it was clear that he and Balotelli had formed an effective strike partnership at the front of Prandelli's favoured 4-3-1-2 formation: not just the combination of a big man and a little man, but that of two players who can not only beat a man and shoot but can pass the ball with a clear vision of what is going on around them.

Their respective temperaments are very different but that might be no bad thing. It is clear that Rossi has a craftsman's diligence in his approach to football but there is also an ability to play the sort of dramatic role more normally associated with his partner: when Fiorentina found themselves two goals down at home against Juventus in October, he scored a hat-trick that saw his team to a 4-2 victory, consigning the champions and league leaders to their first defeat in the Stadio Artemio Franchi for 15 years. His goal in the 3-0 win over Bologna in mid-December, a dinked volley on the run with his left foot, was worthy of Alessandro Del Piero, another player with whom he is sometimes compared.

His club coach, Vincenzo Montella, the former Roma and Italy striker, recently called him "a genius of football". Whether or not Rossi entirely deserves such an accolade, his qualities are becoming apparent with each passing week of a season in which his 18 league appearances have been marked by 14 goals, making him Italy's leading scorer. Montella's only criticism is that he has a habit of turning up late for training. "Sometimes I turn a blind eye," the coach said.

Rossi was born in Teaneck, New Jersey, the son of teachers who had been born in Italy, and after he had played as a schoolboy for the Clifton Stallions, a local team, his family recrossed the Atlantic when he was 12 so that he could join Parma's youth squad. At 17 he was signed by Ferguson and made his Premier League debut for United in October 2005, scoring in a win at Sunderland before being sent on a unsatisfactory half-season loan to Newcastle in the summer of 2006.

The rest of that season, back on loan with Parma, brought greater dividends: nine goals in 19 appearances. And having recognised that he would not be breaking into an Old Trafford squad whose strike force of Cristiano Ronaldo and Wayne Rooney was about to be enhanced by the arrival of Carlos Tevez, he accepted a transfer to Villarreal in the summer of 2007 and spent the next few years scoring 54 goals in 136 appearances in La Liga, finally establishing himself as a player for the top flight.

Or almost. An anterior cruciate ligament injury cost him six months of the 2011-12 season, and a repetition in training shortly after his return sidelined him for a further 10 months. It was last January, during his convalescence, that Fiorentina agreed a four-year deal for his services, with a fee of €10m and a €35m release clause. When his new club opened this season against Catania, he duly scored his first goal in 23 months. Since then he has not stopped; the absence through injury since mid-September of Mario Gomez, the big German forward who came from Bayern Munich to be his strike partner, has hardly been noticed.

"Congratulations to the club on taking the risk of buying him when he was still recovering," Fabio Capello told the Gazzetta dello Sport last week. "Now he's a great addition to the national team."

After Serie A's winter break, lowly Livorno will be the opponents when Fiorentina resume their campaign at home on Sunday. A club that went into administration and suffered relegation to the fourth tier of Italian football barely a decade ago now stands fourth in the table, ahead of both the big Milan clubs, consolidating last year's finish just outside the Champions League positions. When Gomez returns to partner Rossi in front of a midfield including the reborn Alberto Aquilani and the experienced pair of Massimo Ambrosini and Joaquín, they will be hoping to challenge Rafael Benítez's Napoli for the third spot, which would provide further evidence of their progress under the stable ownership of the Della Valle family, owners of the high-end Tod's footwear brand.

Rossi is known by the diminutive "Pepito" in Italy, but is he really that small? He stands 5ft 8in, just as Montella did in his heyday, making him taller than Andrés Iniesta, Lionel Messi and Jack Wilshere by roughly an inch and a half, an inch and just over half an inch respectively. As England may learn next summer, and as Sir Alex Ferguson might now be persuaded to accept: if you're good enough, you're big enough.