Some games stick in the mind more than most. One of the greatest I recall watching while growing up happened on a sunny spring day in Turin in April 1997. It was between Juventus and Udinese and caught the imagination because the outcome left many in the stands scratching their heads.


Shortly after kick off, it looked like the result was a forgone conclusion. Regis Genaux’s red card meant Udinese were down to 10 men and at the mercy of Juventus, who were the reigning Champions League holders and on course to reach another final as well as reclaim the Serie A title from Milan.


The writing, it seemed, was on the wall.


Yet Udinese coach Alberto Zaccheroni out-maneuvered his opposite number, Marcello Lippi. Instead of taking off a striker and bringing on a defender to form a 4-4-1, he sprung a surprise. He left three-at-the back and withdrew one of his strikers into midfield, but on the condition that when the team had possession, he’d resume his former role up front.


Juventus did not know how to react to what was ostensibly a 3-4-2. They were beaten heavily 3-0, as Marcio Amoroso and Oliver Bierhoff both found the net in the five minutes before and after half-time.  Any resistance Zaccheroni had met when proposing a three-man defence to his players earlier in the season crumbled. They embraced it, went undefeated for the remainder of the campaign and finished fifth then third the following season.


Zaccheroni got the Milan job on the back of that success and led them to the Scudetto in 1998 with a three-man defence made up of Bruno N’Gotty, Alessandro Costacurta and Paolo Maldini. He claims to be not the last but “perhaps the only” coach to win the title in Italy by using the tactic. There’s a degree of self-interest in that assertion, and Osvaldo Bagnoli might have something to say about it, but it’s also fair to argue that no one is more associated with the three-man defence in Italy than Zaccheroni.


I mention this because, after the relatively successful re-emergence of the tactic under Gian Piero Gasperini at Genoa and Edy Reja at Napoli, both of whom of course achieved promotion with three-man defences in 2007, it is no longer an odd exception in Serie A but a clear trend across the league as a whole.


The tipping point appears to have come at the end of last season. Walter Mazzarri’s Napoli finished third and qualified for the Champions League group stages using a 3-4-2-1 while Francesco Guidolin’s Udinese followed close behind them, ending the campaign in fourth place after adopting a 3-5-1-1.


Were the other teams missing a trick? Judging by their reaction it seems like they certainly think so.


In addition to Napoli and Udinese there are now seven other teams in Serie A from Fiorentina and Parma to Genoa and Novara basing themselves around systems with three-at-the-back. The list does not include Inter, who started the season with a 3-5-1-1, which they abandoned after a brief and ill-fated spell under Gasperini because it didn’t suit the players. Nor does it take into account the occasions Juventus have swapped their 4-1-4-1 formation for a 3-5-2 in a clear attempt to adapt to their opponents when faced with Napoli and Udinese.


Some have also made the case that Roma use three-at-the back too, but that’s simply the evolution of their 4-3-3 under Luis Enrique with Daniele De Rossi dropping between the centre-backs once the team has won possession in order to provide extra cover in defence and give license to the full-backs to push on and support the attack.


The question remains though: what’s behind the revival of the three-man defence in Serie A. Wasn’t it pronounced dead not too long ago?


In some respects, it’s circumstantial: Take for example, Vincenzo Montella. He opted for a 3-5-2 at Catania because he found himself without any full-backs. He even went so far as to convert Davide Lanzafame, a striker, into a right wing-back out of necessity. Bologna coach Stefano Pioli made a similar decision based on an appraisal of the resources at his disposal. He decided upon a 3-4-1-2 because, in his opinion, it best suited the characteristics of his players.


On the other side of the spectrum there are coaches like Gasperini, who appear to be wedded to a tactic and are dogmatic rather than pragmatic about using it even if it doesn’t fit the team. In his four seasons at Genoa, for instance, he used a back four just 20.4% of the time. Serse Cosmi also falls into this category of three-at-the-back fundamentalists. He has played that way more or less since his time in charge of Perugia in 2000. So is it really any surprise that Lecce are currently lining up in a 3-5-2?


However, for a tactic to be this widespread in Italy there must be a more profound contextual reason as to why it has suddenly become so popular again. The rise of the three-man defence perhaps coincides, at least in Serie A, with the fall of one-striker systems. Ever since Luciano Spalletti left for Zenit St. Petersburg and José Mourinho departed for Real Madrid, the most fashionable formation on the peninsula has been the 4-3-1-2. To put that into some kind of perspective, it was used more than 100 times in Serie A last season.


A three-man defence works especially well in this situation. Rinus Michels once claimed that teams should always have one defender more than the opposition had forwards, and that’s certainly the case when a three-man defence comes up against two strikers.


This is a solution to the problem posed so often in Serie A last season by teams matching up against each other in a 4-3-1-2. In this scenario, there is no attacking width to speak of and the game inevitably becomes a pitched battle in midfield. When faced with a 3-5-2, a team playing 4-3-1-2 finds itself in difficulty, as the wing-backs can exploit the space on the flanks without worrying about their defence. This is because a 3 v 2 situation means there’s a spare man, who can, if he sees fit, either sweep up or bring the ball out of defence and create an attack.


Guidolin alluded to this in a tactical discussion with Il Corriere dello Sport.


“The aspect that convinces me the most about a three-man defence,” he said, “is not so much the desire to be more covered in central areas but the part played by the three defenders in winning back possession, because if they do it well and one of the three manages to get into the other half of the pitch, you always put your opponents in difficulty.”


Elaborating on this point, Zaccheroni added: “In the medium and long term, games are always lost in central midfield and this tactical solution allows you to have a very dense one at that… The return of this kind of defence is borne out of the desire not to lose the battle in the middle of the pitch. The use of a three-man defence is not to add an extra striker to the team but an extra midfielder.”


This debate isn’t confined to Italy either. Pep Guardiola no less has taken it to the extreme at Barcelona, experimenting with a 3-1-3-3. Against Santos in the Club World Cup final in December, he essentially went without a natural striker and played with five midfielders plus Lionel Messi, who defies categorization as a classic centre-forward.


Guardiola’s reasons for using a three-man defence are slightly different from those held by his peers in Italy. Yet it’s clear that, though once considered out of date, the tactic is now back in fashion.


It seems three is once again the magic number.


This article first appeared on Fox Soccer