Roberto Mancini called on every available asset to bring the Premier League title to Manchester City at the death last season, but his use of an Italian physiotherapist who has always liked players to try his donkey stew is one of the lesser known of them.

The individual in question, Sergio Vigano, answered the City manager's call for help only 40 days before City's D-day appointment with Queen's Park Rangers and seems to have doubled up as something of a guru at Carrington, judging by his work for Mancini at Sampdoria, Lazio and Internazionale – whose entire squads would decamp to his base at Monferrato in northern Italy to recharge, eat stew and agnolotti pasta. Vigano, whose presence behind the scenes at City during that astonishing title finale is revealed in a new Mancini biography, believes the players' tensions last April and May caused the club additional injuries and paints a picture of how – behind the scarf – the manager was experiencing serious mental turbulence. "Mancio really suffered," Vigano says. "He was tense. He had to put up with an incredible amount of stress."

This story reveals two important clues to the real Roberto Mancini. His last-minute call to an old friend, despite his club bestowing every conceivable resource upon him over the past three years, shows how he only really trusts Italians. (His assistant, David Platt, is considered an adoptive one.) And the emotion bubbling way beneath the surface insouciance last spring reflects how he is so often on the edge. Several of those interviewed by the biographer Luca Caioli wonder how the impetuous, highly-charged Mancini – who fought with Trevor Francis in the Sampdoria dressing room, thumped a defender twice his size in a schoolboy game and barricaded himself in his room when Bologna would not release him to play for Italy's Under-21s – actually wound up as a football manager at all.

There is no better source on this subject than Sven Goran Eriksson, the mentor who did more than anyone to help the player acquire the mental faculties required to make the transition. "He was a really peculiar guy," Eriksson tells Caioli. "On the football pitch he had quite a strong temper. If he saw that his team-mates weren't doing things right, he went berserk. He never took it out on his opponents, only his team-mates. But I had no doubts he would be a great manager [because] he loves football. Lives for it."

Graeme Souness, who joined the Sampdoria party for a few years in the mid-1980s, describes Mancini as someone who just "didn't want to listen" to much advice. "I'm quite surprised he's turned out the way he has, because he's a very impressive football person now…"

Mancini's belief that only he can be right – even in his mid-teenage years in the Bologna youth set-up, he would disappear off in a temper when training session free-kicks could not be taken from the left, to suit his natural right foot – was born of the fact that he was an enfant prodige. He really ought to have been on Milan's books by the age of 13. Some remarkable twists of fate have marked his 47 years, not least the fact that he survived a clumsy caesarean birth, in which he arrived in the world not breathing and was pronounced dead before a doctor immersed him in ice-cold water and slapped him. But the most fateful twist in his footballing life came when Milan, impressed by him at a trial at Milanello, sent their subsequent letter to the wrong youth club, an error which only came to light years later when the moment had gone.

The road not taken delivered him to Sampdoria and a near lifetime helping football's non-achievers to achieve – City being the latest to fit the pattern. Perhaps only those who were absorbed with Channel 4's Football Italia in the 1990s will really know the Serie A might of the one they called Il Bimbo ('The Boy'), who left home to join Bologna at 13 and was sold to Sampdoria, the highest bidder, for 1.5bn lire.

Caioli's book reminds us of how the man known variously as "Mr Billion Dollars" and plain "Bobby Goal" soared after he had persuaded the manager to make him a goal provider. "He'd developed this wish, this skill to always give the last pass," says Gianluca Vialli, his great running mate from the Sampdoria years. Eriksson is fond of quoting an Argentine saying, where Mancini is concerned: "You can do whatever you want to stop him playing but in 90 minutes he will always fool you twice."

The fight with Francis came soon after the Englishman arrived from City. An on-field argument broke out about a pass Mancini was expecting from Francis which did not arrive, and the two came to blows in the dressing-room.

But referees got the worst of it. A Signor Boschi, from Parma, who had wrongly awarded a penalty to Atalanta against Samp in 1987 was treated to this post-match offering from Mancini: "Boschi is useless. We complain about football violence but supporters should really start thinking about beating up referees instead of clobbering each other." It was an unmitigated rant and only in the aftermath, when suspended for three games, did Mancini plead for understanding. "Those of you who call me a 'football terrorist' should try walking in my shoes," he said. "All the time, the next match is inside your head, that match you cannot afford to lose… then you do lose it in such a way that – for once in your life – you blow up."

Could this man really be a manager? Eriksson tells how Mancini badgered him for knowledge and the roles the protégé assumed at the Swede's Sampdoria – captain, tactician, kit-designer and organiser of the weekly team dinners at La Piedigrotta on the Genoese quayside – always hinted at someone who wanted to explore pulling the whole thing together.

The level of abuse Mancini received as he learned the new trade in Italy explains why he wafts away talk of the pressure attached to the next big game against Manchester United, or Champions League ties like next Tuesday's in the Bernabeu. While he was keeping a virtually bankrupt Fiorentina alive, in his first managerial assignment, Mancini encountered four shady middle-aged characters, all known to the police, as he returned to his house one night. "You don't know shit" was the politest comment he heard. He resigned soon afterwards. When he had arrived in Milan to manage Massimo Moratti's Inter, after three years over-achieving at Lazio, a group of that club's fans, angered by Champions League elimination at Villarreal, were lying in wait, faces concealed by scarves, at Malpensa airport after the club's league trip to Ascoli. After ironic clapping, midfielder Cristiano Zanetti was hit across the back of the head. And that was the season in which Inter were awarded the title, after the Calciopoli match-fixing scandal saw other clubs penalised or sent down the leagues.

The abuse was one of the reasons why England was always such an enticement, despite the prosaic draws of home – his beloved pastime of yachting, family holidays on the Adriatic coast at Senigallia, 30 kilometres from his birthplace of Jesi and the vincisgrassi pasta dish from the Adriatic Marche region which is the speciality of his mother, Marianna. In November 1995, after his bad period with referees and a suspension, Arsenal seemed ready to do anything to bring Mancini to Highbury and he came very close to that move before finding the ties with Sampdoria too binding. Only 13 months later, Eriksson wanted to take him to Blackburn Rovers after signing a preliminary contract with Jack Walker to manage the club.

The course of his three years managing City have so far been an uncanny mirror of his four-year tenure at San Siro – first delivering the domestic cup, then a long-awaited domestic title captured in his third season. It is the Champions League and its forebears which have always been the elusive ones, competitions where failure has drawn heavily on Mancini's emotions and his spirit. Sampdoria's defeat to Barcelona at Wembley in 1992, on a night when Mancini played poorly, drove him to such fury with the referee that a four-match ban ensued. Quarter-final defeat to Rafael Benitez's Liverpool in 2008 led to his unexpected declaration of an intention to resign.

Mancini's Carlos Tevez moment, when his fury with the Argentine drew him close to tears in Bayern Munich's Allianz Arena press hall last September, fits the same mould. "Winning the Champions League would be grand," Mancini tells Caioli in the interview which concludes this book. "It is one of our aims but we need time for that, together with patience." Mancini has not always possessed that quality but he is surely learning. He has always known which assets to draw upon.

Roberto Mancini – A Footballing Life, by Luca Caioli, is published by Corinthian Books, £12.99

Roberto sees red: Mancini's moments

Summer 1984, North America

A 20-year-old Mancini decided to celebrate his first Italy appearances with a night on the town in New York. Accompanied by Marco Tardelli and Claudio Gentile, he broke his curfew, angering head coach Enzo Bearzot. A lack of an apology cost him his place in the 1986 World Cup squad.

May 1991, Internazionale v Sampdoria

As part of a Sampdoria side going for a first Serie A title, Mancini's temper came to the fore at San Siro. Throwing himself to the ground in order to win a penalty, he remonstrated with the referee when it was not awarded and clashed with Inter players, earning a red card with more than half the match left.

Nov 1995, Internazionale v Sampdoria