As chapters in a Champions League adventure go, this could hardly have been less romantic. Better sides than Leicester will fall at Estádio do Dragão, and it spoke warmly of their achievements that Claudio Ranieri could afford to field a skeleton lineup for what could have been their toughest Group G assignment, but the aftertaste was not meant to be this bitter.

The shame in this hammering, confirmed by two goals from André Silva either side of slick finishes from Jesús Corona and Yacine Brahimi before Diogo Jota completed the rout, is superficially slight but Porto could not have dreamed of more supine opposition against which to ensure their own progress to the round of 16. Any thoughts of a pick-me-up before the meeting with Manchester City on Saturday were exposed as fantasy and Ranieri was tellingly downbeat when reflecting on a night that only added to the impression of a malaise within his squad.

“I wanted to give a great chance to our players but it was too easy for Porto. I am very, very sad,” Ranieri said. “OK, we can lose, but not in this way.” Riyad Mahrez, Jamie Vardy, Robert Huth and Islam Slimani were all left at home to stay fresh for a Premier League campaign that has threatened to render last season’s buoyancy a distant memory and their replacements came nowhere near a level that might shake their out-of-touch peers into life. That it took Iker Casillas a full 31 minutes, at which point he was obliged to play a goal kick 20 yards to his right, to touch the ball told enough of Leicester’s application.

The tone was set within six minutes. Ben Hamer, in goal for the first time since January 2015, might have appreciated the early warming of palms from Brahimi’s deflected cross but the resulting corner offered him less practice. Jeffrey Schlupp certainly had Silva under close guard as Corona delivered but, preferring to shove rather than mount a challenge of note, was rooted as his opponent shrugged him off to nod past an exposed Hamer.

By the 20th minute Leicester had barely left their own half and such was their opponents’ domination that when Silva, lifting Maxi Pereira’s cutback over, missed glaringly shortly afterwards it was hard to sense any potential regret.

The impression was confirmed in thrilling fashion. Schlupp was again unconvincing in the challenge as Alex Telles bustled past him towards the left byline but there was plenty of work for Corona to do when the Brazilian’s cross found him beyond the back post. He made light of it; the volleyed connection, with the laces of his left foot, could not have been sweeter and nor could the ball have arced more perfectly into Hamer’s top corner.

Brahimi skewed wide but would not wait long for something more substantial. Leicester were operating at training pace, doing no service to the notion that individual reputations might be enhanced by bright showings here, and were carved open again a minute before half-time when the right-back Pereira was allowed to overlap untracked. The Porto players were queuing up but it was Brahimi, executing a difficult chance on the run, who backheeled cutely ahead of Hamer.

Schlupp’s replacement by Marc Albrighton for the second half was no surprise; Ahmed Musa’s by Leonardo Ulloa was more eyecatching for the simple reminder it proved that the forward had been on the pitch. The changes brought some early improvement, an Albrighton sortie resulting in Demarai Gray’s half‑volley over the crossbar, but it quickly proved illusory.

Danny Drinkwater’s 64th-minute foul on Silva was punished by the forward’s unfussy finish from the spot, before Jota exposed Ben Chilwell to run through and finish comfortably 13 minutes from time.

“I know it is not easy, you don’t play and suddenly you play an important match in the Champions League against a great team, but you have to do something more,” Ranieri said of the 10 players who had not started Saturday’s defeat at Sunderland. “The fault is mine, I put all my players out to show what they can do. The result is my fault, it is important to be clear about this.”

They were words that seemed light years away from the levity with which Ranieri could afford to pepper his speech a few short months ago. He could at least take heart from a full 90 minutes for Nampalys Mendy, the intended replacement for N’Golo Kanté, who had been injured since August, but Leicester may need more than a replica of last season’s midfield dynamo to play themselves back into shape.