Chelsea and Manchester City have adopted this formation but it was a fraught night in Basel that caused the former Liverpool manager to set a growing trend

In a modern world in which style so often matters more than substance – and at times neither seems to matter much at all – moments of significance can be lost amid the swirl. It’s easy to dismiss Brendan Rodgers’ last full season at Liverpool: the ineffectiveness of Mario Balotelli, the falling out with Raheem Sterling, the final-day humiliation at Stoke … and yet it also included a nugget of genuine tactical innovation. It’s not to say that Antonio Conte, Pep Guardiola or Serbia’s Slavoljub Muslin have copied Rodgers or have in any way learned directly from him to point out that all have, this season, employed some of his model with success – and Rodgers, it might also be pointed out, was inspired by Paulo Sousa.

Rodgers, the story went, was fretting after Liverpool’s 3-1 defeat away to Crystal Palace. Balotelli had proved himself unwilling or unable to lead the press. Rickie Lambert didn’t seem mobile enough to do so. Rodgers turned over ideas in his mind, sustained only by tea and toast. He kept thinking back to the 1-0 defeat against Basel earlier in the season, when an injury to Behrang Safari led them to switch to a back three. Basel’s new shape caused Liverpool, operating a 4-2-3-1, major problems.

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At an abstract level, all tactics are about space. Where is it? How can it best be denied the opposition? How can it best be exploited?

4-2-3-1 is popular because it achieves a fairly regular spread of players across the pitch and is flexible. It does, though, have one obvious potential weakness: that space between the wide forwards and the full-backs, outside the two holding midfielders but too narrow for the full-backs to combat without risking leaving a channel outside them for an opposing full-back or wing-back to overlap into. No blanket is ever quite big enough to cover all of the pitch and, with a 4-2-3-1, that’s where the principal gap is. It’s also there in a 4-3-3 unless the midfield three lies very deep and even, to an extent, in a 4-4-2.

Playing two creators in that three-quarter line in the old inside-forward positions naturally exploits that pocket and immediately creates confusion in an opposing 4-2-3-1. It could be argued that two holding players should be able to combat them as wing-halves once did but that risks them being dragged out of position, creating space for a centre-forward dropping off or a runner from deep in that most vital zone, the central area just outside the box.

That those channels between the centre-back and the full-back are vulnerable is no great revelation. The vast majority of strike pairings would look to probe in those areas. Pulling them deeper, into the gap between defensive and midfield zones, complicated matters for the defending side even further, which is why the Christmas Tree formation, the 4-3-2-1, pioneered by Co Adriaanse at Den Haag, practised briefly by England under Terry Venables and dissected in his Coverciano thesis by Carlo Ancelotti, enjoyed a surge of popularity in the early 90s.

The problem with the Christmas Tree, though, was that, even with attacking full-backs, it lacked width and so was relatively easy to shut down. This was what Rodgers recognised watching Basel after Derlis González had come on for Safari. Add a third centre-back and the full-backs could be pushed much higher, as wing-backs and beyond.

And so was born the 3-4-2-1.

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Liverpool never quite got the defensive side of the formation right but Philippe Coutinho and Adam Lallana prospered in those inside-forward roles, with Sterling a nominal centre-forward who could drop back and exploit any space they created by dragging holding midfielders out of position. Liverpool played like that first away at Old Trafford and, thwarted by David de Gea, lost 3-0. They took 33 points from their following 13 games, though, before morale collapsed in the final couple of weeks of the season.

Eden Hazard and Pedro have benefited from a similar formation at Chelsea in the last five games – and they do seem very quickly to have got the defensive part of the system right, helped in no small part by the tireless work of N’Golo Kanté in protecting the back three.

At Manchester City, the most constant theme (positionally) in Guardiola’s selections this season has been to have a pair of inside forwards (or “free eights” as Kevin De Bruyne, perhaps following his manager, has called them). His preference is for the wide players to be much higher, but he too uses a block of five players as a base, whether a back four with a holder that forms a 3-2 shape when in possession (either by the holder dropping and the full-backs tucking in, or by a central defender stepping up) or, more straightforwardly, a back three and two holding midfielders. Serbia too, under Muslin, have taken to deploying Dusan Tadic and Filip Kostic in inside-forward roles behind Aleksandar Mitrovic in a 3-4-2-1.

In time, history suggests, opponents will work out a way of combatting that twin playmaker threat but, for now, it is a potent weapon still in its infancy, a means of exploiting weaknesses that had long lain unexposed in systems that use a back four.