When the noise had subsided, the victors and vanquished departed, when Anfield was at last silent, empty and still, the question remained: why? What was it that possessed a defender as experienced as Kolo Touré to take fright, to be so terrified at the prospect of lasting just six minutes at this remarkable arena that he should give away the penalty that cost his team the game and the dream of a first Champions League crown?

And the answer will come back: it was Liverpool. It was this club, this particular team, and what they have come to represent in Europe. Touré was disturbed by the legend of a Liverpool who will not lie down, who return from the dead like The Shape in John Carpenter’s Halloween films. Remember that scene in the pitch-black bedroom when the monster rises again, his white mask all that is visible in the darkness? On nights such as this, Liverpool are like that: unstoppable, remorseless, their power inexplicable.

They were beaten, make no mistake of that; or they should have been. In the 84th minute, when Emmanuel Adebayor tapped a cross by Theo Walcott into a net guarded only by José Manuel Reina, the goalkeeper, as Liverpool’s defence lay scattered across the field, the score on the night was 2-2 and the game was over.

Arsenal were going through on away goals and Chelsea lay in wait. What followed defied explanation, or belief. From the next attack, the very next attack, Ryan Babel, the Liverpool substitute, broke down the left, strode into the Arsenal penalty area and Touré pulled him back. Why? Only he knows. It cannot have been pace because defenders deal with pace all the time. It cannot have been Babel’s fearsome reputation as a marksman, either; no Ian Rush, he. Maybe even Touré doesn’t know what possessed him. Who knows why rational people fear the bogeyman?

The penalty was given in an instant by Peter Fröjdfeldt, the referee from Sweden. Steven Gerrard stepped up, struck the ball to the right of Manuel Almunia, the goalkeeper, and scored. Soon after, Babel held off Cesc Fàbregas to give the scoreline a conclusiveness it did not entirely deserve, but that will become part of Liverpool’s mythical status, too.

Looking at the Barclays Premier League table, scrolling through a grisly roll call of victims, there is no logical justification for their presence in the last four of the Champions League, just as there was none for their path to the final last year, or in 2005. They beat better teams on the way, won in circumstances when other teams would have surrendered, were given the last rites and pronounced dead at the scene, before grabbing the attendant by the throat on the slab in the morgue, making everyone jump.

Yet while the particular circumstances may elude reason, to scratch beneath the surface of this win, look at the second Liverpool goal. It was the reason Arsenal were so jittery, the distilled essence of everything Rafael Benítez, the Liverpool manager, was trying to achieve. The finish, a thing of grace and beauty from Fernando Torres. The set-up, a route-one clearance with more than a hint of old-style Wimbledon from Reina. In between, the merest touch from the pylon-like presence that is Peter Crouch. Combined, it should have won the game for Liverpool. Tellingly, it was always intended to.

Managers bristle at being given the long-ball label, but it is no criticism to say that Benítez set his team up in a manner as unorthodox as anything seen in this country since Graham Taylor’s first spell at Watford. He played, in essence, 4-2-4 with Gerrard and Dirk Kuyt kept consistently high on the flanks, Gerrard coming inside from dead balls and clearances only to allow Crouch to use his height against Touré, Arsenal’s makeshift right back.

The jury is out on the extent of the touch Crouch got to Reina’s long kick in the 69th minute, but it did its job in unsettling the Arsenal defence and allowing Torres to turn, with far too much space in the penalty area, before lashing his shot past Almunia. It was this targeting of Arsenal’s defensive weakness that Liverpool had been searching for.

Often, it was not pretty to watch, and purists would have got most out of the first 25 minutes when Arsenal passed Liverpool off the park — as they did here earlier in the season — but Benítez has since fashioned the best way to beat Arsenal and he stuck to it right up until the last 12 minutes when he removed Crouch, introduced Babel and, irony of ironies, pace won him the game.

Benítez will not see it that way, of course. He will insist that his direct tactics earned Liverpool a 2-1 lead that should not have been surrendered, and he has a point. The problem with his game plan initially was that it relied heavily on getting the ball up to Crouch for knockdowns and by its nature that can make play haphazard.

Against this barrage, Arsenal’s intricate passing game looked even more alien. Had so many of the trappings around Anfield not belonged to the branded, packaged billion-dollar industry that is 21st-century football, this could have been a European Cup tie from the 1970s: one team continental in origin, the other as English as pudding and rain in July. The difference was these Englishmen were mostly foreigners, marshalled by a Spaniard.

The game was made by the fact that Arsenal scored from the first clear-cut chance of the night, an outstanding sequence of passes that resulted in the ball pinging around the outskirts of the Liverpool penalty area before finding its way to Alexander Hleb. He played Abou Diaby in and the Frenchman, included at the expense of Robin van Persie, the forward, beat Reina with a ferocious shot at his near post.

Gradually, Liverpool began to apply the aerial pressure that has caused problems for Arsenal this season. In the 30th minute, a left-sided cross by Fábio Aurélio, the full back, took a deflection and was palmed out for a corner by Almunia. Gerrard took it, Sami Hyypia lost Philippe Senderos, perhaps for ever, and headed into the far corner, where Fàbregas came up short, in the true sense of the phrase, much like Arsenal’s season.

Liverpool (4-2-4): J M Reina — J Carragher, M Skrtel, S Hyypia, F Aurélio — X Alonso, J Mascherano — S Gerrard, P Crouch (sub: R Babel, 78min), F Torres (sub: J A Riise, 86), D Kuyt. Substitutes not used: C Itandje, A Voronin, Y Benayoun, Á Arbeloa, Lucas Leiva.

Arsenal (4-4-1-1): M Almunia — K Touré, W Gallas, P Senderos, G Clichy — E Eboué (sub: T Walcott, 71), F Fàbregas, M Flamini (sub: Gilberto Silva, 41), A Diaby (sub: R van Persie, 71) — A Hleb — E Adebayor. Substitutes not used: J Lehmann, A Song, N Bendtner, J Hoyte. Booked: Senderos, Touré.

Referee: P Fröjdfeldt (Sweden).