Liverpool fell to a 2-0 defeat in Naples in their opening group-stage game of the 2019/20 Champions League.
The Reds began the defence of the European Cup with another loss at the hands of the Italians just as they did last year despite a spirited display.
A controversial penalty decision gifted Napoli the lead, adding fuel to the conversations already being had about VAR, before Fernando Llorente capitalised on a rare mistake from Virgil Van Dijk to make it 2-0 in stoppage time.
VAR takes centre stage as dubious penalty swings tie
Last season's trip to the Stadio San Paolo saw Liverpool produce a turgid performance, bereft of their usual attacking verve. Here, Jurgen Klopp's side were much improved from that sobering night, with both sides showing strong defensive resilience.
Making his debut in the competition, Adrian continued to impress, rivalling Alisson for the best save to be made against the Italian side. Clawing away Dries Mertens effort with a strong right hand, it was a brilliant show of athleticism and focus, reacting mid-dive to deny the hosts. Elsewhere, Van Dijk commanded his usual authority across the back-four, instilling a sense of calm while making a series of timely interceptions to break up the attacks. Ahead of him, Fabinho was in inspired form, producing one of his best performances to date.
The Brazilian was relentless in the first-half, persistently pressing and showing great positional intelligence to stifle the danger. At the other end, proactive passing and awareness laid the foundations for Liverpool's attacking ventures.
However, it was up front that The Reds weren't quite at their glistening best. Indeed, they lacked their usual ruthlessness, with Roberto Firmino guilty of not passing after a promising breakaway before Sadio Mane missed an opportunity to pull the trigger.
Both sides were neck and neck throughout, giving as good as they good until referee Felix Brych's decision swung the game in the latter stages. Andy Robertson was the culprit, adjudged to have fouled Jose Callejon inside the area, but it looked a soft call with the forward appearing to already be on his way to the deck before the Scot made any contact.
Jurgen Klopp reflects on Napoli defeat
Albeit a blow in the first game of this year's competition, Liverpool will take a lot of encouragement from the manner of their performance, which offered a stark improvement on last year. Should they continue to play as they did, you'd expect them to surge through the Group stages without any hiccups.
Speaking after the match, Jurgen Klopp was keen to highlight the positives in his team's performance against Carlo Ancelotti's side.
"It was much more of a game than last year when we played here and lost 1-0," Klopp said, via the club's official site. "We had a lot of good moments; I think we controlled the game in a lot of moments, we had a lot of interceptions, we won the ball and had counter-attacks. Both teams showed a lot of respect for each other, very compact, defended well and that’s how you play a game against a strong side, to be honest."
"The second half was a bit [more with] wilder moments - counter-attack, counter-attack and then lose the ball when you are in the box and then have to run back. Then we started to control the game again and then we conceded the 1-0 and that was the game-changer tonight."
The German pinpointed the penalty decision as the pivotal turning point in an otherwise tight contest.
"I said last week after the Newcastle game if it would have been decisive then I could have discussed it. Now it was decisive, and I could say a lot of things about it but I would look like a bad loser and I am not."
"It is a decision made by human beings. I think when you see the pictures it is clear. What can I say about it? It was very decisive in that moment for sure, but we cannot change it anymore."
Elsewhere, Red Bull Salzburg breezed past KRC Genk, leaving Liverpool in third place on goal difference. Klopp's side will now turn their attentions back to the Premier League, hoping to maintain their perfect start with a win at Stamford Bridge on Sunday.