Lorenzo Insigne scored a dramatic 90th-minute winner as Napoli stunned Liverpool with 1-0 victory in the Champions League group stages.
Insigne struck in the final minute of normal time, converting Jose Callejon's inch-perfect cross on the stretch to spark wild celebrations at the Stadio San Paolo.
After Dries Mertens struck the crossbar, it was no more than Carlo Ancelotti's team deserved, having dominated the second half against a below-par Liverpool side, who lost Naby Keita to injury in the first half.
The victory lifts Napoli above Liverpool into top spot in Group C, which is now wide open following Paris Saint-Germain's 6-1 thrashing of Red Star Belgrade earlier on Wednesday.
Jurgen Klopp's team, having seen a credible point snatched from their grasp, have just four days to dust themselves down for Sunday's showdown with Manchester City - live on Sky Sports.
Napoli: Ospina (7), Maksimovic (6), Koulibaly (8), Albiol (7), Rui (7), Allan (8), Hamsik (7), Fabian (6), Callejon (7), Milik (6), Insigne (8).
Subs: Zielinski (5), Mertens (6), Verdi (5).
Liverpool: Alisson (8), Alexander-Arnold (6), Gomez (8), Van Dijk (7), Robertson (5), Milner (6), Wijnaldum (6), Keita (5), Mane (6), Salah (5), Firmino (6).
Subs: Fabinho (5), Henderson (6), Sturridge (n/a).
Man of the Match: Lorenzo Insigne.
Liverpool's performance was symptomatic of a side that - with a victory already on the board - did not need to win, and an uneventful first half littered with possession errors unfolded.
Keita's loose back pass on 11 minutes was pounced upon by Napoli and switched to Insigne, but he flashed a left-footed effort wide of Alisson's post.
Liverpool then lost Keita to injury on 18 minutes, his replacement Jordan Henderson tried to inject some vigour in midfield but Napoli withstood the brief revival.
The visitors had Alisson to thank on 33 minutes as he parried Arkadiusz Milik's shot on the swivel and gathered at the second attempt before the rebound was converted.
Napoli made three changes from their 3-1 defeat to Juventus as Arkadiusz Milik, Nikola Maksimovic and Fabian returned. Naby Keita replaced Jordan Henderson in Liverpool’s only change from their 1-1 draw at Chelsea.
Napoli upped the ante in the second half with the addition of substitute Mertens. After Callejon saw a volley cleared off the line by Gomez, the Belgium international crashed an effort off the underside of the Liverpool bar.
With a point in sight, Liverpool's attacking presence steadily diminished as they failed to register a shot on target through the duration of the game.
That strategy backfired in the final minute as Napoli made their pressure tell. Callejon raced in behind the advanced Andrew Robertson and beat Alisson with a low cross which was poked home by Insigne, leaving Liverpool with no chance to respond.
- Napoli have won nine of their 13 Champions League group stage home games (D2 L2).
- Liverpool failed to muster a single shot on target in a Champions League game for the first time since February 2006 (0-1 vs Benfica).
- Liverpool lost a Champions League game thanks to a 90th minute winner for the first time since December 2009, when Alberto Gilardino scored for Fiorentina.
- Napoli's Lorenzo Insigne has scored four goals in his last six Champions League games - more than he had in his first 15 in the competition.
- David Ospina has kept a clean sheet in both of his Champions League games for Napoli - just one fewer than he managed in 13 starts with Arsenal in the competition.
Carlo Ancelotti: "We interpreted the game really well. We were able to keep possession. Overall it was a very good approach from the team, there was a perfect balance to avoid the attack and managed their strong strikers up front. It gives a lot of character to the team and it's great we kept the same mentality from the start to the end. It gives great self-confidence to the players."
Jurgen Klopp: "No attempts on target, I don't remember when that happened last time. I think we had a big part of that because we can play much better. No shot on target is not enough. They had a good game, we didn't, that's what they deserved the three points."
Man of the Match - Lorenzo Insigne
A constant thorn in Liverpool's side, Napoli's local hero Insigne got his just rewards for a display of sheer persistence. The diminutive forward registered a game-high five efforts on goal and, had it not been for Virgil van Dijk and Joe Gomez, he would have secured a much-needed victory sooner than he did.
Live Renault Super Sunday
Liverpool resume their Premier League campaign with a mouth-watering Renault Super Sunday clash against champions Manchester City - live on Sky Sports Premier League. Napoli host Sassuolo in Serie A on Sunday.