That trip to the Stadio Artemio Franchi resulted in a 2-1 victory for the home side, with the Bianconeri outplayed by a slightly above-average version of La Viola.
That game saw Fiorentina coach Paulo Sousa get everything right and his players execute perfectly on the field. By the same token, the cautious, defence-first approach Juve adopted, intrinsic to their 3-5-2 formation, was taken apart by a proactive and aggressive opponent who were spurred on by the vociferous Curva Fiesole.
However, rather than write the result off as a freak occurrence, Juve boss Massimiliano Allegri reacted with a solution that has rocked the established order of European football to its core.
"I made the choice after the Fiorentina match because I thought it was right to give something more to the team and to allow the team to express its full potential," the coach said at a recent press conference. "The lads did well, because, at the end of the day, when you have a group of lads who all make themselves available, it's easier to get results.”
And results have followed. Juventus have drawn one and won 12 of their Serie A fixtures since that loss in Tuscany, also eliminating AC Milan and Napoli to reach the Coppa Italia final and securing a place in the last four of the UEFA Champions League with a two-legged victory over Barcelona.
By adopting a 4-2-3-1 system that allows him to field all of his quality attacking players while masking their shortcomings in midfield, the Juventus boss has ensured his side remain impenetrable in defence while also being much more dangerous themselves.
It is a move that has seen the Bianconeri not only maintain and extend their lead at the top of the Serie A table but also fired the Old Lady to the forefront of a shift in the tactical approach of the continent's elite clubs.
Leicester City remarkably won the Premier League title last term by ensuring their defence was organised and protected. Atletico Madrid have been utilising a similar approach for some time now under Diego Simeone.
Perhaps nowhere has this change in philosophy been more fully embraced than at Chelsea. Antonio Conte only arrived last summer, and despite the presence of tactical geniuses like Manchester City manager Pep Guardiola and Liverpool boss Jurgen Klopp, the Stamford Bridge outfit are clear at the top of the league.
Having finished in 10th place last term and looking like a broken team, Conte has—with only minor turnover in the squad—transformed Chelsea into an unstoppable machine. Blues defender Gary Cahill is in no doubt as to what is behind the improvement, as he explained in August during an interview with the official Chelsea website:
We've added one or two quality players which is great but predominantly it's the same players from last year, and when we won the league the season before
The main thing for me is how fit and sharp we look, and the organisation in terms of where players need to be. I felt like last year we were all over the place at times. We've got discipline, we're organised and we look fit. I'm in the best condition I've been for a long time.
The manager is adamant about the way he wants to play and that’s what everyone has to buy into.
It is that same attention to detail and steely determination to succeed that typified Conte's time at Juventus, but the Italian club has undoubtedly taken it to an even higher level since parting company with the Lecce native in the summer of 2014.
After reaching the Champions League final in his first season in charge at Juventus Stadium, Allegri has repeatedly refined his tactical setup while integrating a growing list of new arrivals. From Conte's last season in Turin, only six players—Gigi Buffon, Leonardo Bonucci, Andrea Barzagli, Giorgio Chiellini, Stephan Lichtsteiner and Claudio Marchisio—remain, and it is no surprise that five of them play at the back.
Lichtsteiner has been replaced in the first-choice starting XI by Dani Alves, a move that mirrors Alex Sandro's emergence on the opposite flank. And the two Brazilians add pace and verve to the attack while remaining defensively resolute.
That balance is repeated throughout the regularly deployed side shown above. Gonzalo Higuain tracks back and presses opponents more than he has done previously in his career, with Paulo Dybala providing a creative outlet behind him.
Out wide, the attacking intent of Mario Mandzukic and Juan Cuadrado—who provided a crucial outlet whenever Juve won possession against Barca—is tempered by their willingness to sacrifice for the team. As can be seen in the image below, whenever Juventus lose the ball, that duo drops in to ensure the Bianconeri are not outnumbered in midfield.
Both protect the full-backs behind them expertly, while Mandzukic negates countless corners and free-kicks by getting his head to the ball before the opposition can punish Juve.
Make no mistake, however. This is not the Catenaccio, a term that is badly misused, of the 1960s and '70s. The Bianconeri press high up the pitch whenever possible, with the graphic below showing how they deny opposing teams the time to play out from the back when the opportunity presents itself:
Having been at the club since 2005 and spending time under the guidance of Fabio Capello, Didier Deschamps, Claudio Ranieri and Conte, among others, Chiellini has played in a vast variety of systems and enjoyed great success, yet he too has been impressed by Allegri's impact.
"What matters most about this formation is reducing the space from front to back; the forward players have helped us massively in achieving this and the defensive work they do is very important," the Italy international told Bleacher Report. "By closing the gaps between the lines of defence, midfield and attack, we have become much more compact."
That was clearly evident at the Camp Nou, with Juventus emerging with a clean sheet against a Barcelona side that had won their previous four Champions League home games by a combined score of 21 goals to one.
Key to that were Sami Khedira's efforts to deny Sergio Busquets the ball and Miralem Pjanic's diligent tracking of Lionel Messi. The former is so often the hub of Barca's play but was merely on the fringes of this game, while the Argentinian megastar was reduced to hopeful long shots.
It was unquestionably a defensive performance to be proud of, and one that piqued the interest of Inter Milan legend Tarcisio Burgnich. A hard-nosed and uncompromising defender who played for the Bianconeri in the early 1960s, he was part of the Grande Inter side that won two European Cups and four Serie A titles, making him an ideal man to discuss the recent tactical shift seen at Juve, Leicester and elsewhere.
"Defending is essential if you want to build a solid, winning team," he told Bleacher Report. "I don't think the playing style of the teams you mentioned will ever influence the approach of other great sides like Barcelona, Bayern, Real Madrid, Arsenal and Ajax. However, there comes a time when—with the right personnel within a system, with a more organised defence as part of a team that plays direct football or on the counter attack—the clubs you mentioned can beat or cause serious problems for any other side."
Burgnich then gave his opinion on the quality of Juventus, and the Nerazzurri legend explained how he saw each of the individual players: "First of all, that defence is brilliant because they have an outstanding goalkeeper and their back line is perfectly balanced. They boast the technical ability and leadership of Bonucci, along with Chiellini's tireless ability to carefully mark his opponent and his combativeness in every challenge.
"They have a nice foil in Barzagli, who's one of the most complete players in his position in European football. This Juventus side is strong in every area and don't appear to have any weaknesses. Their mental strength has been amazing thus far in the way they lead and dictate matches without showing too much respect to the most prestigious sides."
It is difficult to disagree with any of that, and something even deeper has become clear in light of Barcelona's recent demise. Talk of what the Catalan giants need to do moving forward will rage for months, particularly with coach Luis Enrique already revealing he will leave at the end of the season.
There is an end-of-an-era feeling about this incarnation of the Blaugrana, and perhaps their most recent conquerors have shown the wider footballing community a glimpse of the future.
They slayed Barcelona. Conte's Chelsea have left Guardiola—the undisputed Godfather of tiki-taka—trailing in their wake. It's a new day, one peppered with elite teams who are not merely defensive but who place a heavy emphasis on getting things right at that end of the field first.
Allegri and Juventus have, by virtue of their consummate victory over Barca, singled themselves out as the vanguard of the latest direction the sport looks set to take. At the Camp Nou, they put the world on notice: A revolution is coming, and it is led by an Old Lady in black and white.