And they had the misfortune to run into a little bit of genius, in every sense, as Mo Salah added a second with another brilliant goal, a gliding, dancing finish that made things look ridiculously easy.
It gave the Reds their biggest ever points total in a Champions League group, with 15…and also showed that even at half strength they are more than a match for most Euro opponents.
Jurgen Klopp has now used 56 players in his 65 European games as Liverpool manager, and the latest to be blooded in the Champions League were summer signing Ibrahima Konate, and 19 year old Tyler Morton.
Morton has made quite the impression in the junior ranks at the Merseyside club, and there were glimpses of why, as produced an assured first 45 minutes.
If Morton is the promising future, then Thiago is very much – finally – the here and now for Liverpool, after overcoming the injury problems which have dogged his Anfield career so far.
Against a Porto team who looked dangerous going forward, but less enthusiastic out of possession, he was able to showcase his full range of talents, with sublime passes, shimmering dummies…and THAT finish.
It was worth the admission fee alone, even with the likes of van Dijk, Alexander-Arnold, Henderson, Fabinho, Robertson and Jota rested.
It was a free kick on the right from Alex Oxlade-Chamberlain, only partially cleared by Otavio, and the little Spain international met it with exquisite technique, that saw the ball kiss the turf and accelerate into the net.
The technical phrase is, he creamed it. Or perhaps something slightly less printable. It was only his second Liverpool goal, but by God it was worth the wait, a radar-evading heat seeking missile that cruised just above ground level.
Porto had their moments either side of half time, but the truth is, that an understrength Liverpool side were still far too good, showing the gulf in class that is growing between the Premier League and the rest of Europe.
They could have had more, but Salah emphasised the gulf when he jinked inside brilliantly onto sub Jordan Henderson’s fine pass to leave defenders on their backside and the ball in the net.