Practically since its incarnation, three-man defensive systems have been deemed incompatible with the Premier League and most particularly its biggest clubs.

Sir Alex Ferguson rarely exceeded flirting with the notion of 3-5-2 variations during his near three decades at Manchester United, defensive injuries have seen Arsene Wenger exclusively put square pegs in round holes rather than daring to venture into the tactical unknown over the last twenty years and Roberto Mancini's Manchester City reign capitulated after he tried to introduce the system at the start of the 2012/13 campaign. Even the most significant formational innovation in Premier League history, Jose Mourinho’s utilisation of the lone frontman, maintained English football’s long-standing flat back four tradition.

Yet, three-man defences are suddenly in vogue amongst the Premier League’s elite, with two managers acting as the standard bearers - Manchester City’s Pep Guardiola, employing a 3-6-1, and Antonio Conte, tweaking his Juventus playbook to create Chelsea’s 3-4-3. Whilst the former’s is very much a work in progress, suffering a six-game winless streak and still lacking appropriate individuals for key roles, the latter’s implementation has rebooted the Blues’ season.

Indeed, from four outings in the 3-4-3 system, Chelsea have won four, scored eleven (including four against Manchester United), kept four clean sheets and conceded less than ten efforts at goal per match. The switch has instantaneously made the west Londoners ruthlessly efficient at both ends of the pitch - and most importantly, propelled them back into a title race that appeared to be slowly slipping away.

So why has Conte triumphed so quickly where others have failed, what does it tell us about a rapidly changing Premier League and should rival teams be mimicking his approach?

Well, there's no doubt Conte represents a rather unique case study. A three-man defence was the cornerstone of his three consecutive Serie A titles at Juventus and brought him positive performances, although not always results, with Italy at Euro 2016.

Although other Premier League managers have been well-versed in the system - such as Louis van Gaal, who attempted to bring it to Manchester United - Conte is a three-at-the-back specialist. He knows how to implement it, how to teach it on the training ground, how to embellish its strengths and hide its weaknesses. Few, if any, top-end Premier League managers have been better qualified.

As a consequence, Conte tailored Chelsea’s squad accordingly in the summer. The initially scoffed-at swoops for David Luiz, who has excelled in the midfield-joining central defensive role, and wing-back Marcos Alonso have now been justified. Guardiola’s squad isn’t quite there yet, on the other hand, the defence and the flanks being the ultimate weaknesses.

Meanwhile, one of the reasons three-man defensive systems are now working, or at the very least more popular, in the Premier League comes down to the numbers game - namely, the attacker-to-defender ratio - as a result of Jose Mourinho’s aforementioned introduction of the solitary striker.

The theory is simple enough; why have four men marking a single front-man, when three can do the job just as well and free another for further up the pitch? That couldn’t have happened when the Premier League was still obsessed with strike partnerships and 4-4-2s, but now represents an innovative solution to a long-standing trend of lone centre-forwards.

Conversely, however, the ease in which Chelsea have adapted to the seemingly alien system, and the manner in which it has drastically improved their performances, is sourced from a traditionally English ideal: the four-man, box-to-box midfield.

Indeed, Victor Moses, Nemanja Matic, N’Golo Kante and Marcos Alonso are all completely different types of player - a winger, a powerhouse, a nippy playbreaker and a first-and-foremost defender respectively - but it’s their stamina and energy, not to mention their shared simplicity in styles, that has made them such a cohesive unit in an incredibly short space of time.

Whilst Chelsea’s defence has been impeccable and the inside forward roles are getting the best out of Eden Hazard and Pedro (and subsequently, Diego Costa), the box-to-boxers are the real glue holding it all together.

And much like how three-man defences are often perceived as alien, the initial assumption is that box-to-box quartets belong to the Premier League’s yesteryear. But consider Leicester City last season: the most traditional and basic of 4-4-2s, galvanised by a relentlessly energetic midfield, turned relegation battlers into reigning champions. Of course, there were a multitude of other factors, but four-man midfields are by no means outdated as they may seem if put into the right context.

That’s what Conte has done at Chelsea, suggesting his 3-4-3 system is adoptable for other Premier League clubs. After all, what side doesn’t have four box-to-box players within their ranks? What side doesn’t have two wingers who like to tuck in, and what side doesn’t have three centre-backs? As much as Conte has modified his squad to get the maximum out of his tactics, with specialists in certain positions, most clubs should have make-shift imitations already at their disposal. Even Conte is currently relying on an ad hoc wing-back in Victor Moses.

So will the Premier League's next tactical shift be towards three-man defences? Overall, I'm not quite so convinced. English players received their footballing educations in 4-4-2 and 4-5-1 variations and as it did for managers of prior Premier League generations, that will inevitably throw up problems for certain teams. Likewise, whilst modern day footballers are highly adaptable, there's no doubt Conte benefits from the number of players who his formation perfectly. That will be tough to recreate exactly without spending in the transfer market.

But nonetheless, Conte is defying the myth that three at the back doesn't belong at the Premier League's summit and in the context of this season's title race, it makes his Chelsea side a rather unique, intriguing and unpredictable animal. Could a three-man defence finally win the Premier League? We'll have to wait and see.