NAPLES, Italy (AFP) - Lorenzo Insigne struck late as Napoli snatched a 1-0 win over an outclassed Liverpool side described as "not good enough" by coach Jurgen Klopp in a Champions League Group C game at the Stadio San Paolo on Wednesday (Oct 3).

Carlo Ancelotti's team had piled the pressure on last year's finalists before finding a way through on 90 minutes when Jose Callejon broke down the right crossing for Insigne who beat Alisson in the Liverpool goal.

"We weren't good enough," said Klopp. "It's a bad sign if you say that your goalkeeper was your best player.

"No attempt on target? I don't remember when that happened last time. At the moment I have to accept a big part of their performance was my fault.

"It looked not like it should have looked."

The win puts Napoli top of Group C with four points from two games, with Paris Saint-Germain a point behind after thrashing Red Star Belgrade 6-1 earlier.

Liverpool had been top of the group after their 3-2 win over PSG two weeks ago with Napoli held 0-0 at Red Star.

But Klopp's side now drop to third.

"We interpreted the game well, we studied the opponent without taking anything away from our identity," said Ancelotti.

"We had an extra central defender and were able to build the game from the back. There was a perfect balance.

"We showed it would be would be hard for everyone in this group. It remains very complicated but after the disappointment of Belgrade it gives us confidence."

The visitors never really settled into the game and suffered an injury blow when midfielder Naby Keïta went down early with a back problem and was stretchered off in tears.

The Guinean - making his first Champions League appearance for the club - had been the only change in Klopp's side from last weekend's draw at Chelsea.

Keita took the place of Jordan Henderson, who came on after the Guinean's injury after 20 minutes.

Ancelotti opted for a 3-5-2 attack with Nikola Maksimovic coming into the back line.

Captain Marek Hamsik started next to Fabian Ruiz and Allan in midfield, with Arkadiusz Milik preferred to Dries Mertens up front alongside Insigne and Callejon.

The hosts defenders pinned back Liverpool's strike force of Roberto Firmino, Mohamed Salah and Sadio Mane.

Liverpool goalkeeper Alisson had his work cut out on his return to Italy after his move from Roma last summer.

Napoli's top Serie A scorer Insigne came close twice early, with Alisson comfortably saving a Milik header just before the break.

The hosts kept up the pressure after the break with Insigne crossing for Milik, who lashed towards goal on 50 minutes, but Joe Gomez came to the rescue after Alisson spilled the ball.

Gomez again did well to clear a goal-bound Callejon effort off the line with Dries Mertens rattling the woodwork with Alisson well beaten with eight minutes to go.

But Insigne finally shook off Virgil van Dijk to score the winner to deafening applause from the 41,000 crowd.

"(I'm) not shocked. We didn't adapt, that happens," said Klopp.

"There wasn't that much pressure from Napoli, it looked like they were constantly on us but it wasn't.

"Napoli used the atmosphere. We couldn't calm it down with our performance."

Ancelotti added: "I said to my players 'just enjoy yourselves, the Champions League doesn't happen every day so just have fun.

"This is an important victory because it shows a progression, especially in terms of mentality."

The victory maintained Ancelotti's record of having never lost in the Champions League against Liverpool with four wins now and a draw.

Ancelotti's AC Milan beat Liverpool in the final to lift the title in 2007.