They had been more measured, enjoyed greater balance and built off defensive solidity after the 4-1 humiliation at Tottenham, which was followed by 13 goals in four games with just one breach of their backline.
Only nine minutes later, the Spaniard stuck out a leg and conceded a penalty, which the French forward converted. Sadio Mane is played through on goal with a long ball over the top.
And in the final seconds Guido Pizarro grabbed an unlikely equaliser to cap a remakrable comeback. Sevilla meanwhile travel to Maribor for their final group-stage fixture.
The champions will be through with a win remember.
You don't mind Real Madrid scoring beauties pas you but when you let one centre-half nod it on and the other one head in from two yards it's a bit poor.
Game, set and the match, surely.
He's comfortably been the best signing of the summer in the Premier League, but it is mad to think that he was Liverpool's fourth choice to begin with.
Captain Jordan Henderson repeated his manager's line about stopping playing football and was at a loss to explain the collapse, saying the team couldn't cope in the second-half.
They scored two almost-identical goals from left-wing corners delivered by Philippe Coutinho, Firmino on hand at the back post to turn home Georginio Wijnaldum's flick-on and break the deadlock after just 88 seconds. The 3-0 scoreline slightly flatters Liverpool considering the two huge chances that Sevilla could not convert, but it the Reds were also exceptionally dangerous on the counter. However, it was an all too familiar story as poor defending cost Klopp's men yet again on a night they could have qualified for the last-16 of the Champions Leeague.
"They fought back, so big credit to them, but we have to do it differently", Klopp added.
Liverpool's attacking players are brimming with confidence but their defence remains a worry.
The hosts had their chances to get back into the game when Loris Karius got a fingertip to Nolito's goalbound effort to turn the ball onto the post before Ben Yedder fired inches wide with just the German goalkeeper to beat. It was a goal to make Klopp wince.