Match ends, Leicester City 1, Liverpool 2.
Liverpool manager Jurgen Klopp said Alisson's horrendous error "was clearly going to happen one day", after his side maintained their 100% start to the season with victory at Leicester.
Klopp's team looked on course for a comfortable win when, after Mohamed Salah had uncharacteristically missed an open goal, Sadio Mane pounced in the penalty area to poke Liverpool in front after only 10 minutes.
Liverpool's position looked even more secure when Roberto Firmino stole in on James Milner's corner to double their advantage with a header on the stroke of half-time - but they then proceeded to make life difficult for themselves.
The main culprit was Alisson, the £67m summer signing from Roma, who was embarrassed as he gifted Leicester a goal after 63 minutes when he was robbed by Kelechi Iheanacho while inexplicably performing an elaborate turn with the ball at his feet in the area, Rachid Ghezzal scoring following the ensuing chaos.
Leicester pushed for the equaliser but Liverpool closed out victory to make it four wins out of four at the start of a league season for the first time in 28 years - and leave Alisson the most relieved man inside the King Power Stadium.
"It was clearly going to happen one day," Klopp said of Alisson's error. "I didn't think it was going to happen in the next match [after his successful showboating against Brighton last time out, when he chipped an onrushing attacker]. It's all OK. He knows he could have cleared the situation.
"I said last week we need to get used to it. Don't constantly give the goalkeeper the ball, there are other solutions. He's a fantastic goalkeeper who makes fantastic saves and of course in this situation he did not do what he should have done, but it's all good."
Liverpool win - but suffer in victory
Liverpool can call on an old saying to bolster their confidence even further after making it four wins from four at the start of the Premier League season - namely it is a sign of champions that you can still win when well short of your best.
And this certainly applied here, with Klopp's side mediocre for long periods, yet still emerging victorious in the face of Leicester's spirited challenge.
Liverpool opened in the sort of blistering fashion that has blown teams apart in the past, with Salah missing an open goal even before Mane pounced on a rebound off Harry Maguire to score.
They then, surprisingly, became subdued, only to score against the run of play as Firmino guided in Milner's corner on the stroke of half-time.
Liverpool looked rocky under pressure as Leicester stepped up the pace after the break, with even the normally unflappable Virgil van Dijk rattled as he was put under a thorough examination.
They could not control midfield, while Salah was, for once, totally out of sorts and could have had no complaints when he was eventually replaced by Xherdan Shaqiri.
For all that, Liverpool dug deep and secured another three points in a season when they and Klopp know there will be little or no margin for error.
On another day Salah will shine, their defence will be in control and Alisson will not make the sort of horrendous error that turned up the heat on Liverpool even further.
There will be days throughout Liverpool's season when the result will over-ride the performance - and this was undoubtedly one of them.
Alisson has to learn quickly
Alisson has already raised eyebrows and attracted attention for his confidence with the ball at his feet, notably his willingness to audaciously chip an oncoming Brighton attacker during last weekend's victory at Anfield.
There is, however, a time and a place - and the time he chose at the King Power Stadium was definitely not it.
Alisson was trying to be too clever by half when he embarked on a dainty turn and backheel as Iheanacho chased down Van Dijk's slightly wayward backpass.
For all the modern thinking, this was an occasion when the big boot should have been applied - as Klopp's emphatic gesture on the touchline subsequently suggested. Alisson decided otherwise, played himself straight into trouble and the whole calamity ended with Ghezzal scoring. It gave Leicester the sort of opportunity that could have proved very costly.
Liverpool have suffered enough at the hands of goalkeeping errors, such as those of Loris Karius in the Champions League final, so this moment will have revived some uncomfortable memories.
Liverpool spared Alisson's blushes by holding on for the three points but you suspect the Brazilian will be on the receiving end of a sharp reminder from Klopp not to repeat those sorts of mistakes.
Alisson himself insisted afterwards he will not make the same error again, describing it as a "reading the play mistake".
"I didn't receive that good of a pass. We talked about that in the locker room," he added.
"I won't be stupid to make the same mistake. It's part of my game. I won't be arrogant, saying that I will keep doing this. We have to learn from our mistakes.
"I think that it was a foul, but we can't support ourselves on that. In this kind of play, here in the Premier League, not every collision is a foul."
'If you're a forward you are not going to get fooled'
Former Newcastle and England captain Alan Shearer on Match of the Day:
His manager said he has got away with the mistake and that is fine, but he got away with one at Brighton last week as well.
If you're a forward and you have seen the footage against Brighton, you are not going to get fooled again. The Leicester player gambles and gets the reward.
Alisson should be getting rid of that ball and there was no need to do it. They were in cruise control but then the panic sets in and it was unnecessary. He won't make that mistake again.
Leicester show real fighting spirit
Leicester, having kept faith with manager Claude Puel, have made a promising start to the season with victories at home to Wolves and at Southampton following an opening-day defeat at Manchester United.
And here, despite the home defeat, there was plenty for Puel and his players to take from a display that showed real character and determination, especially without suspended main striker Jamie Vardy.
The Foxes could have been forgiven for thinking the fates were against them when Firmino made that crucial intervention to give Liverpool a two-goal lead right on half-time.
Leicester, however, regrouped and gave it a real go after the break in the sort of manner that suggests more good things than bad lie ahead of them this season, which was reflected in the generous reception their supporters gave them at the final whistle.
Man of the match - Joe Gomez
Match of the Day pundit Martin Keown: "Gomez is a real talent. Today he was better than Van Dijk and that's some compliment. His mobility, the way he floats across the pitch, he can pass the ball, has the technique and the vision. He has everything in his game. Gareth Southgate must be licking his lips to work with him because he is an immense talent."
'We were a little lucky, but we deserved to win' - what they said
Liverpool manager Jurgen Klopp speaking to Sky Sports: "We could have scored earlier in the game, I said a few times in the past a dry pitch means not good football. Leicester wanted to be aggressive but couldn't because we moved so well. We were in a few situations a little lucky, but think we deserved to win."
Leicester manager Claude Puel speaking to Sky Sports: "I'm disappointed for my players because they gave their best. The second half was fantastic, we showed good quality and had a lot of chances. We had good tempo, good aggression. We played with confidence and we had the chances to come back. It is encouraging."
Mane loves facing the Foxes - the key stats
- Mane has had a hand in four goals in his past four league games against Leicester (two goals, two assists).
- Liverpool have not lost an away league game when scoring first since December 2016, when they were beaten 4-3 by Bournemouth.
- Milner has now registered 80 Premier League assists, the same as David Beckham. Only six players have more in the competition.
- No player has assisted Firmino more times in the Premier League than Milner (eight).
- Under Klopp, Firmino has been directly involved in 60 Premier League goals (37 goals, 23 assists), 15 more than any other Liverpool player.
- Leicester are the first Premier League team to have three different Algerians score for them (also Riyad Mahrez and Islam Slimani).
- Since the start of last season, no player has more assists in the top four tiers than James Maddison (16). The former Norwich man is level with Kevin de Bruyne and Barry Douglas.
- Leicester have lost their past 11 Premier League matches against sides starting the day top of the table, scoring just five goals while conceding 27 in those matches.
After the international break, next up for Liverpool is a trip to Wembley to play Tottenham in the early game on Saturday, 15 September (12:30 BST), while Leicester face Bournemouth at the Vitality Stadium later that day (15:00 BST).
- 14Ricardo Pereira
- 24MendyBooked at 88mins
- 25NdidiBooked at 90mins
- 31GhezzalBooked at 61mins
- 10MaddisonSubstituted forAmarteyat 83'minutes
- 11AlbrightonSubstituted forIheanachoat 61'minutes
- 7GraySubstituted forOkazakiat 76'minutes
- 66Alexander-ArnoldSubstituted forMatipat 89'minutes
- 4van DijkBooked at 55mins
- 14HendersonSubstituted forKeitaat 71'minutes
- 7MilnerBooked at 90mins
- 11SalahSubstituted forShaqiriat 71'minutes
- Paul Tierney
- Shots on Target
Second Half ends, Leicester City 1, Liverpool 2.
Wilfred Ndidi (Leicester City) is shown the yellow card for a bad foul.
Foul by Wilfred Ndidi (Leicester City).
Naby Keita (Liverpool) wins a free kick in the defensive half.
Corner, Leicester City. Conceded by Virgil van Dijk.
James Milner (Liverpool) is shown the yellow card for a bad foul.
Ricardo Pereira (Leicester City) wins a free kick in the attacking half.
Foul by James Milner (Liverpool).
Corner, Liverpool. Conceded by Harry Maguire.
Substitution, Liverpool. Joel Matip replaces Trent Alexander-Arnold.
Nampalys Mendy (Leicester City) is shown the yellow card.
Sadio Mané (Liverpool) wins a free kick in the attacking half.
Foul by Nampalys Mendy (Leicester City).
Attempt blocked. Wilfred Ndidi (Leicester City) right footed shot from outside the box is blocked. Assisted by Kelechi Iheanacho.
Foul by Sadio Mané (Liverpool).
Nampalys Mendy (Leicester City) wins a free kick in the attacking half.
Attempt missed. Trent Alexander-Arnold (Liverpool) right footed shot from outside the box is high and wide to the right.
Substitution, Leicester City. Daniel Amartey replaces James Maddison.
Attempt missed. Sadio Mané (Liverpool) header from the centre of the box misses to the right. Assisted by James Milner with a cross following a set piece situation.