Unsettled Liverpool edged past battling Leicester 2-1 after Alisson’s howler threatened to blow their 100 per cent record.
First-half goals from Sadio Mane and Roberto Firmino put Liverpool in control at the King Power Stadium before the hosts hit back thanks to Alisson’s gaffe.
His error, which saw him robbed of possession by Kelechi Iheanacho and resulted in Rachid Ghezzal slotting home, was the first goal the Brazilian has conceded since his £67million summer move from Roma.
But Liverpool survived to record their fourth straight win and continue their flying start to the campaign.
Leicester battled well and worried the visitors but failed to cash in once they had Liverpool on the ropes.
Ultimately, the Foxes paid the price for a slow start and Mohamed Salah missed a sitter after just four minutes when the usually lethal forward sidefooted wide from 10 yards after Kasper Schmeichel denied Firmino.
Salah’s slip was a collectors’ item and Mane showed him a clinical edge just six minutes later.
There had already been some worrying gaps in the Leicester defence and Mane capitalised on a lucky ricochet to open the scoring.
Andrew Robertson bundled his way down the right and Harry Maguire deflected his cross to Mane and the forward poked past Schmeichel.
A goal up, Liverpool settled and dominated, toying with their hosts as Firmino and Salah waltzed through the Foxes’ lines and Georginio Wijnaldum’s effort was blocked by Maguire.
Leicester had gained a foothold, at least, but it was whipped from under them a minute before the break.
Schmeichel, making his 300th appearance for Leicester, turned Salah’s curling effort behind before Firmino pounced.
Leicester defended the initial corner but when James Milner swung the ball in from the other side Firmino brushed off Maddison’s weak challenge to head in.
At 2-0 it was a long way back for the hosts but Maddison almost started the revival six minutes after the break only for Joe Gomez’s excellent covering tackle to deny him.
Wes Morgan then failed to get a proper touch on Ben Chilwell’s cross with Alisson exposed.
Leicester sensed a way back and they grabbed a goal after 63 minutes thanks to Alisson’s calamitous mistake.
The Foxes forced Liverpool into retreat and while Van Dijk’s back-pass pushed Alisson wide the Brazil international was too slow to clear.
His attempt to turn Iheanacho only allowed the striker to steal the ball and cross for Ghezzal to net from six yards.
Liverpool had failed to get going in the second half — missing a four-on-two chance just before Ghezzal’s goal — and paid the price.
But Leicester could not find a second as Jurgen Klopp’s Reds clung on to all three points.
