Five unanswered away goals – three from the boot of Sadio Mané plus one each for Roberto Firmino and Mohamed Salah, who scored his 30th of the season – have effectively snuffed out any hint of competition what, after December's draw, was thought to be an evenly-matched tie. The return leg at Anfield in a fortnight should be a mere formality.
The day before this game, Klopp tentatively discussed the prospect of meeting and at least competing with the likes of Manchester City or Paris Saint-Germain in a later round but on this performance, he was being too modest. No last-16 outfit will want to be drawn against Liverpool in the quarter-finals given this sort of devastating form.
It was only, arguably, the initial stages which did not go entirely their way. Backed by a boisterous if somewhat sparse home crowd, the hosts had all the early running. Otavio almost capitalised when Dejan Lovren failed to cut out one cross, but the Croatian recovered quickly enough to deflect the effort over his own crossbar.
Porto not only looked adventurous in Liverpool’s half but combative and well-organised in their own. Led by a midfield shield of Sergio Oliveira and captain Hector Herrera, Conceicao’s ‘back six’ left Klopp’s attack to feed on scraps. They were unfortunate that when the visitors’ first shot of note came their goalkeeper failed them.
To break the deadlock will be a significant confidence boost to Mané, who has looked strangely out-of-sorts of late, but he had Jose Sa to thank. The opposition ‘keeper allowed an eminently stoppable strike from the inside-left channel to fall through his hands, pop out behind his head and trickle over the line.
Liverpool, for their part, had a valuable away goal and cared little how it came. Their second would follow four minutes later and was significantly more spectacular.
Salah was surprised as the rest of the Estadio do Dragao when James Milner struck the far post with a curling effort, and that might explain the delayed reaction that prevented him from scoring first-time on the rebound.
No matter. Though his first touch was clumsy, his second was immaculate and deft enough to guide the ball around the onrushing Sa and his outstretched right hand. Another Porto defender rushed in to block but it was already too late. After a slight header to set himself, the Egyptian stroked the ball into the empty net and became the 13th Liverpool player to reach 30 goals in a single campaign.
It was not even half an hour into their home leg of this tie and Porto now had a sizeable task on their hands but they ended the half with more promise. Francisco Soares should have reduced the arrears minutes before the break when put through on Loris Karius’ goal. He could only place a limp shot wide.
Had that chance been taken, it may have set Liverpool up for a long and arduous second half, of the type they suffered on their last European trip in Seville. Instead, Klopp’s side increased their lead shortly after the interval, hitting Porto with one of their characteristic counters.
It began with a splendid one-two, as Salah repaid Firmino’s backheel on the halfway line with a perfect through ball to put Liverpool’s frontman through one-on-one. Sa was equal to the subsequent effort, parrying it down low to his left but into the path of Mané. The Sengalese finished from a tight angle.
Three unanswered goals up, memories of that night in Andalusia last November when the same lead was squandered might have returned. ‘Pizjuanbul’, as it was called, raised plenty of questions about Liverpool’s game management. Yet as Klopp himself might argue, the best way to protect a 3-0 lead is to score a fourth.
Liverpool did just that as Firmino eventually got himself in on the act 69 minutes in, converting Milner’s daisy-cutting cross from the left with a well-taken finish. It meant that Klopp’s side became the top scorers of this short Champions League campaign so far, with 27 goals to their name.
There was still time for a 28th. In the final five minutes, Mané ensured he would take the match ball home, beating Sa with a thunderous strike from distance after a quick exchange of possession with substitute Danny Ings. It was another spectacular goal, and the climax Liverpool’s emphatic return to the latter stages of this competition deserved.