The last time Liverpool were 3-0 down at half time in the Champions League was in 2014 to Real MadridLiverpool were thrashed by Napoli in their first Champions League Group A game on a night to forget in Italy.
Jurgen Klopp's side were 3-0 down at half time but it could easily have been more as Alisson saved a penalty and Virgil van Dijk made a goalline block.
Piotr Zielinski put Napoli ahead from the spot in the fifth minute after Victor Osimhen had hit the post.
Andre-Frank Anguissa and Giovanni Simeone extended Napoli's lead, before Zielinski scored again after the break.
It was a terrible opening half from Liverpool as Joe Gomez struggled to deal with Osimhen and was relieved when the Napoli forward trudged off with an injury before half-time.
His replacement, Simeone, needed just three minutes to score on his Champions League debut as Liverpool looked shell-shocked by the home side's relentless forward approach.
There were chances for the visitors - Van Dijk had a header well saved, Mohamed Salah struck an effort at the goalkeeper and a teasing cross bounced dangerously off Harvey Elliott's knee at the back post.
But Liverpool were sloppy in possession - even Salah mis-controlled a good pass from Trent Alexander-Arnold when well-placed in the box - and their defensive mistakes were punished by an expressive Napoli side.
Any hope of a second-half comeback were over when Zielinski chipped a finish over Alisson from close range to make it 4-0 and though Luis Diaz curled in for an immediate response and came close with a diving header, Liverpool were deservedly beaten.
Deadline-day signing Arthur Melo came on for his debut late in the second half and fellow midfielder Thiago returned from injury to make a brief cameo, but Liverpool will head home having now won just two of their last seven matches in all competitions.
More to follow.
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Napoli
Squad number1Player nameMeret
Squad number22Player nameDi Lorenzo
Squad number13Player nameRrahmani
Squad number3Player nameKim Min-Jae
Squad number17Player nameOlivera
Squad number99Player nameZambo Anguissa
Squad number68Player nameLobotka
Squad number21Player namePolitano
Squad number20Player nameZielinski
Squad number77Player nameKvaratskhelia
Squad number9Player nameOsimhen
Squad number6Player nameMário Rui
Squad number7Player nameElmas
Squad number11Player nameLozano
Squad number18Player nameSimeone
Squad number23Player nameZerbin
Line-ups
Napoli
Formation 4-2-3-1
1Meret
22Di Lorenzo13Rrahmani3Kim17Olivera
99Zambo Anguissa68Lobotka
21Politano20Zielinski77Kvaratskhelia
9Osimhen
1Meret22Di Lorenzo13RrahmaniBooked at 66mins3Kim17OliveraSubstituted forMário Ruiat 74'minutes99Zambo Anguissa68Lobotka21PolitanoSubstituted forLozanoat 58'minutes20ZielinskiSubstituted forElmasat 74'minutes77KvaratskheliaSubstituted forZerbinat 57'minutes9OsimhenSubstituted forSimeoneat 41'minutesSubstitutes
5Nunes Jesus6Mário Rui7Elmas11Lozano18Simeone23Zerbin30Sirigu55Östigard59Zanoli70Gaetano81Raspadori91NdombéléLiverpool
Formation 4-3-3
1Alisson
66Alexander-Arnold2Gomez4van Dijk26Robertson
19Elliott3Fabinho7Milner
11Salah9Firmino23Díaz
1Alisson66Alexander-Arnold2GomezSubstituted forMatipat 45'minutes4van DijkBooked at 18mins26Robertson19ElliottSubstituted forArthurat 77'minutes3Fabinho7MilnerBooked at 10minsSubstituted forThiago Alcántaraat 63'minutes11SalahSubstituted forJotaat 63'minutes9FirminoSubstituted forNúñezat 62'minutes23DíazSubstitutes
6Thiago Alcántara13Adrián20Jota21Tsimikas27Núñez29Arthur32Matip43Bajcetic47Phillips95DaviesReferee:Carlos del Cerro GrandeLive Text
Match ends, Napoli 4, Liverpool 1.
Second Half ends, Napoli 4, Liverpool 1.
Corner, Napoli. Conceded by Andrew Robertson.
Corner, Napoli. Conceded by Andrew Robertson.
Foul by Thiago (Liverpool).
Giovanni Simeone (Napoli) wins a free kick in the defensive half.
Attempt blocked. Diogo Jota (Liverpool) left footed shot from the right side of the box is blocked.
Corner, Liverpool. Conceded by Giovanni Di Lorenzo.
Attempt blocked. Arthur (Liverpool) right footed shot from outside the box is blocked. Assisted by Diogo Jota.
Attempt saved. Alessio Zerbin (Napoli) right footed shot from outside the box is saved in the bottom right corner. Assisted by André-Frank Zambo Anguissa.
Corner, Liverpool. Conceded by Mário Rui.
Offside, Napoli. André-Frank Zambo Anguissa tries a through ball, but Giovanni Simeone is caught offside.
Arthur (Liverpool) wins a free kick in the defensive half.
Foul by Mário Rui (Napoli).
Attempt blocked. Giovanni Simeone (Napoli) left footed shot from the centre of the box is blocked. Assisted by Alessio Zerbin.
Thiago (Liverpool) wins a free kick in the defensive half.
Foul by André-Frank Zambo Anguissa (Napoli).
Substitution, Liverpool. Arthur replaces Harvey Elliott.
Foul by Darwin Núñez (Liverpool).
Alex Meret (Napoli) wins a free kick in the defensive half.
