In the Allianz Stadium press room after Kalidou Koulibaly powered home a 90th-minute winner for Napoli to blow the Serie A title race wide open, Juventus head coach Massimiliano Allegri had reached the end of his tether. Asked why his reigning champions, chasing a seventh consecutive Scudetto, were not playing well at a crunch moment in the season, the 50-year-old's face was a picture of perplexed incredulity. "The quality of our play?" he began. "For four years, Juventus have been playing 57 matches a year, you know? I don't understand. How many do the others play? They're finished in December. "Good Lord! They go out of the cup, out of everything else. We play 57 matches a year." Allegri, who will lead Juve in a crunch Derby d'Italia at Inter on Saturday, was just getting started. "Getting to the final of the Italian Cup is not easy, we've done it for the past four years. We've played in the Champions League for the past four years. Twice we've got to the final, twice we've been eliminated late on. "Guys, we need calm. You're making me lose my patience and I have a lot. This is useless for the team." As much as Allegri claimed that such negativity was bad for his players, it was hard to escape the impression things had got personal. He is not wrong to say he has a lot of patience. Discontent at Juventus after the Italian champs opened the door to Napoli? No chance, according to Massimiliano Allegri.#InterJuve #DerbydItalia pic.twitter.com/lSJdxee0w0 — Omnisport (@OmnisportNews) 28 April 2018 The unwanted Milan reject Allegri's reception when he was appointed successor to club icon Antonio Conte on July 16, 2014 could best be described as lukewarm. Sure, he won Serie A with AC Milan in 2010-11 but he also oversaw the ill-fated decision to let Andrea Pirlo join Juventus during the subsequent close season, a move that came to symbolise a power shift in Italian football, with Conte's men motoring towards three straight Scudetti. Six months earlier, Allegri had been sacked with Milan languishing in 11th place, six points above the relegation zone and 30 shy of a galloping Juve. He hardly looked like the man to follow Conte, the inspirational figure who restored pride and glory to Juventus after their fall from grace during the Calciopoli scandal. The former Cagliari and Sassuolo boss duly added title number four to the run and completed a domestic double with the Coppa Italia – a feat his esteemed predecessor never managed. Juve were even dreaming of Champions League glory before Barcelona, MSN and all, pulled away from them to a 3-1 win in an absorbing 2015 final in Berlin. But this was just Allegri the aziendalista, the company man – a reputation he unfairly acquired after Silvio Berlusconi brought him to San Siro and one that stuck as star men headed unchecked for the exit door to hasten Milan's decline – winning with Conte's team. Big deal. A domestic double! #4Ju33 #CAMP10NI pic.twitter.com/ysWTXUl3As — JuventusFC (@juventusfcen) 20 May 2015 Exits, entrances and Allegri's Juventus From the XI that started against Barcelona in 2015, Pirlo, Arturo Vidal and Carlos Tevez played their last games for Juventus. A year later, Alvaro Morata and Paul Pogba departed, while Kingsley Coman had joined Vidal in making waves in Munich and not Turin. Still, Allegri's Juventus kept winning. Two more doubles followed, along with more Champions League heartache in the 2017 final in Cardiff. After that crushing 4-1 loss to Real Madrid, Dani Alves and defensive lynchpin Leonardo Bonucci moved on. Still, Juventus kept winning. Another double is within reach. Despite losing such a prime collection of talent, Allegri's shrewd transfer dealings have reflected the pragmatism and adaptability of his tactical approach. While his Juventus lack the visceral thrills of Conte's blood and sweat operation, they are a more cerebral outfit. Having picked up the reins committed to Conte's favoured 3-5-2, Allegri gradually phased in the 4-3-1-2 he enjoyed success with at Milan to combine the dazzling array of Pirlo, Vidal, Pogba and Claudio Marchisio. A 4-2-3-1, with Mario Mandzukic reinvented as a wide-left attacker, became a feature last season, while the introduction of France international Blaise Matuidi's box-to-box capabilities alongside esteemed playmaker Miralem Pjanic and Sami Khedira has allowed a 4-3-3 at times this term. This flexibility means a Juventus where Paulo Dybala – recent form struggles aside – and Douglas Costa can cause havoc and Gonzalo Higuain can gorge on goals if the mood takes. Alternatively, they can shut down and strangle opponents. It is a triumph of Allegri's coaching and intrinsic feel for the right in-game adjustments. Speed Skill Precision @douglascosta #ForzaJuve pic.twitter.com/ifQe8Z6hPz — JuventusFC (@juventusfcen) April 26, 2018 A worthy rival Another problem Allegri has in terms of receiving due credit is Juventus' monolithic status in Italy. Fuelled by the Agnelli family's Fiat empire and drawing fans from across the country, those who do not love them loathe them. Winning Serie A is, in the eyes of many, simply what Juventus are supposed to do. Napoli's underdog charge under the maverick Maurizio Sarri – despite losing Higuain to big bucks Juve – is one for the romantics. But, as much as Napoli might seem like a colossal nuisance to Allegri as he tends to the mental scars of that heroic failure in Madrid, they might end up being the best thing to happen to a man linked to prime Premier League posts at Chelsea and Arsenal. Great sporting deeds are defined as much by the opponent overcome as the achievement itself. You cannot rank Muhammad Ali without considering Joe Frazier, nor Ayrton Senna independently of Alain Prost. Roger Federer and Rafael Nadal are forever intertwined. Processions to titles can dull the senses. Facing down a swashbuckling Napoli who bloodied Juventus in their own back yard finally gives Allegri a chance to remove any lingering doubt over his elite credentials. It has taken a lot of patience.