It’s early days yet, of course. Nobody should be getting carried away. There’s plenty of time for the second legs or subsequent rounds to make a mockery of the thought but, after a few years in which the big clubs have treated caution as something laughably old-fashioned, a quaint affectation like a waxed moustache or a pocket-watch, might defending be making a comeback?

There were no goals in Tuesday’s two Champions League ties. As yet, nobody has scored a goal in the first half of a Champions League knockout tie this season. Goals per game in the last 16 (with all the obvious caveats about sample size) are at less than two as opposed to five in the knockout phase last season. It’s as though the collective thought has gone round that after last season’s chaos of three-goal comebacks and nearly comebacks, getting the defence right is where teams can gain an edge.

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This is not just a Champions League phenomenon. Liverpool have been notably more cautious in general this season, while Manchester City too have been less inclined to hurl both full-backs forward at once – something seen most obviously in the 0-0 draw at Anfield. After the abandon of last season, the feeling that teams unpractised domestically in defending had forgotten how to do it, the start of this season’s knockout stage has felt like something of a throwback.

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And yet, it is not quite the same as it was. For one thing, an art so long neglected cannot easily be readopted. Players used to hurtling forward at every opportunity are having to learn. At Anfield on Tuesday, the force of will required for the buccaneering Joshua Kimmich and David Alaba to restrain themselves and remain deep was clear. When Kimmich did, on one occasion late in the first half, get caught near the halfway line by Sadio Mané, his immediate reaction was a slightly panicky foul that drew the yellow card that will keep him out of the second leg: he knew his job was not to allow Liverpool to get in behind him.

Besides, the world has changed. Knowledge of what has gone before, developments elsewhere, have changed the pattern of games. This may be a reversion to a more traditional attitude, but that does not necessarily make it ripe for the reintroduction of José Mourinho. Some aspects are familiar. Bayern contentedly wasted time on Tuesday, taking an age over set plays, making sure any treatment they received on the field was as thorough as possible.

Attempts to play the ball square at the back, though, were rather less successful. Back in the 70s and early 80s, when Bayern and Liverpool were at their most successful in Europe, the easiest way to kill a game was for a defence to hold the ball, knowing they could always roll it back to their goalkeeper if they came under pressure. The back-pass law changed that, of course, and playing out from the back is now the hallmark of a team that want to control possession. The problem with that, though, is that these days just about everybody presses – the combination of short passes from goalkeeper to defender and pressing with a conservative mindset leads to something very strange.

Facebook Twitter Pinterest Bayern’s Joshua Kimmich, right, restrained his normal attacking instincts against Liverpool. Photograph: Chloe Knott - Danehouse/Getty Images

By the second half, the game at Anfield had taken on a more conventional pattern, with Bayern’s three central midfielders forming a deep-lying block in front of the back four, but for much of the first half the central third of the pitch saw weirdly little action. That can be the sign of an end-to-end thriller, or of two long-ball teams coming face to face, but here it was the result of two sides concerned not to overcommit and anxious about conceding possession by moving the ball forward too quickly, trying to play out from the back and finding themselves hemmed in by their opponents’ press.

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Manuel Neuer and Alisson are goalkeepers noted for their ability with their feet, both are comfortable in the sweeper-keeper role – Neuer, indeed, could be said to have popularised the modern conception of the position. Yet both had uneasy moments in Tuesday’s first half, finding themselves being closed down without an obvious passing option with the route to their defenders blocked by the press and midfielders reluctant to drop deep and break their shape. Almost every chance in the first half was the result of a turnover in the final third, the attempt at caution on the part of both sides paradoxically making them more vulnerable in what became a bitty game almost entirely devoid of fluidity.

It was not only the away side doing it, even if the consensus was that Bayern had frustrated Liverpool. Without Virgil van Dijk, with Roberto Firmino struggling to shake off a virus, against opponents who sat deep and so negated the pace of their front line, getting away without conceding an away goal isn’t a bad result for Liverpool either – even if there are concerns about their recent away record in Europe.

It was not necessarily defending as Udo Lattek or Bob Paisley would have recognised it. It was awkward, unsteady and at times unconvincing (if, ultimately, effective). But perhaps the wheel is beginning to turn and gung-ho attacking is beginning to yield once again to something more balanced.