“If we have to score five goals to win, then so be it,” Vincent Kompany said when it was put to him that a single Liverpool goal at the Etihad on Tuesday would surely leave Manchester City with too much to do to progress in the Champions League. “We won’t stop believing. We will still take a positive attitude into the game and try to get through.”

One can only admire the City captain’s confidence, though his assessment overlooks the fact that his side did not manage a single attempt on target in the first leg of the quarter-final at Anfield and the consideration that, even had the match gone on until midnight, the visitors might still not have managed to give Loris Karius anything to do.

Based on the first leg, and Liverpool’s appetite for Europe, not to mention Jürgen Klopp’s managerial record against Pep Guardiola, the chances are that Liverpool will score against a City side now obliged to chase a three-goal deficit. The odds on City scoring four or five against a defence that shut them out so effectively in the first leg must be considerably longer. Liverpool will not have the backing of an impassioned Anfield this time, it is true, though they will have the knowledge that after a couple of seasons of trying Klopp has come up with a defensive system that finally seems to work.

The key to that is probably the £75m acquisition of the unflappable Virgil van Dijk, even if the full‑backs Trent Alexander-Arnold and Andy Robertson were the stars of the show in the first game against City. Karius in goal has given some reassurance too. He might have been underemployed in the first leg but his decision-making and communication with the players in front of him is an improvement on Simon Mignolet, whose sometimes erratic goalkeeping tended to undermine confidence. Compared with Nicolás Otamendi, Kyle Walker and others in the City rearguard each member of the Liverpool back line was a tower of strength, though the whole point about Klopp’s defensive system is that it is a system, it is not just about the back line. It starts from the front, as Van Dijk is in a good position to explain.

“The work our front three do defensively, not just attacking‑wise, is amazing,” the centre-half says. “They get through so much work. Look at Bobby Firmino. It is a nightmare to play against him, I can say that myself because I have done it. He chases everything down, all the front three do, and if the midfield do it as well then you are not going to be in trouble. If you can get it right at the front, then obviously you feel the benefit at the back. As a defender you may even have an easy night.”

Van Dijk stopped short of describing last Wednesday as an easy night – “Everybody knows how much quality City have got and in the second half they were pressing us” – and he does not imagine the next leg will be a formality, even with such a lead. “I don’t think anyone believes it is all over,” he says. “We just have to play our game and try to score goals. I don’t think it will be a good idea to sit back.

A season of admirable, elegant simplicity has reached a complicated, urgent conclusion

“We need to be aware and ready for anything, though we can take a lot of encouragement from keeping a clean sheet in the first leg. The key in quarter-finals is not to concede, particularly when you are at home. We knew we had to be tight, and the way we reacted under pressure from City in the second half made me proud. We were struggling at times but we worked hard and stayed together.”

Kompany can talk about belief, though in the decisive 20 minutes of the first half that tilted the tie in Liverpool’s favour and left their opponents looking rattled and disorganised for the second time at Anfield this season, this time without an answer, City did not look like the side with the stronger conviction. Liverpool positively radiated self-belief, as so often happens on European nights at Anfield, with Klopp somehow able to channel the energy of the crowd into asking for and receiving new highs of confidence from his players. There seems no other explanation for the fact that so many players in red had their best games to date, while too many of the players in blue struggled to respond.

Most managers would have considered Alexander-Arnold a risk at right-back, yet the 19-year‑old shone in keeping Leroy Sané quiet. Most critics wondered what Klopp was doing when he spent £35m on Alex Oxlade-Chamberlain at the start of the season – after a devastating first half capped by a fine goal, they now know. Robertson, Dejan Lovren and James Milner were also right at the top of their game and the only worry for Liverpool going into the second leg is that it might be difficult, perhaps even unrealistic, to expect so many players to reach the same level again. Liverpool’s high-pressing style is famously tiring and hard to keep up over the course of a season, though one has the feeling that at the business end of the Champions League they will not be found short of enthusiasm or energy.

Suddenly it is City being asked to dig deep. Guardiola would have liked to be free to concentrate on Europe with the league put to bed but by a matter of days it has not worked out like that. A season of admirable, elegant simplicity has reached a complicated, urgent conclusion, so much so that even the City fans are now expected to do their bit on Tuesday, to do their best to turn the frosty Etihad into the sort of frenzied cauldron Anfield resembled for the first leg. Good luck with that, though at least the City support will not need reminding that their initial attempt to wind up their opponents on Merseyside rather backfired.

It turns out Liverpool do not live in the past after all. Nor are they like Manchester United in the way they approach the Champions League knockout stage. Liverpool come alive in Europe, standing taller than ever. Now City are facing a taller order than they must have anticipated, it is their turn to show they can do the same.