Liverpool will not mind if history repeats and another late defeat in Naples ends the glory of the Champions League, but this was a daunting start to defending number six. Jürgen Klopp's team greatly improved last season's poor performance here and at the top when José Callejón entered the penalty area on penalties. Andy Robertson's clumsy absence brought familiar pain to death.
Dries Mertens converted the penalty after 82 minutes to leave the European champions unrewarded for their improvement. It was a captivating affair with prominent defenders and goalkeepers, but it turned into an unfortunate night for Liverpool when a rare mistake by Virgil van Dijk allowed Fernando Llorente to secure Napoli's victory in the final seconds.
Liverpool's participation in the Champions League was at stake when they met Napoli in their group's last game of last season, but this was a rare example of danger appearing at this stage of the competition. As Klopp's team has shown, it is possible to lose all three group games away from home and still win the Champions League. But the holders had something to prove on their return to San Paolo Stadium after producing the worst performance of a triumphant campaign here last October.
Carlo Ancelotti beat Liverpool that night with two No. 6 and a central defender, Nikola Maksimovic, on the right side. This time, the coach who won and lost the Champions League final against Liverpool opted for a more offensive approach, with Hirving Lozano teaming up with Mertens at the front and Lorenzo Insigne, last season's captain and winner, aiming for Trent Alexander-Arnold at Napoli left. It was an open and highly entertaining contest between two teams willing to commit to numbers at the first opportunity. Having been scoreless for so long largely resulted from the quality of the four defenders on display.
Kalidou Koulibaly is to Napoli what Virgil van Dijk is to Liverpool and the defensive rock of the hosts was the dominant force of the game in the early stages when he halted dangerous attacks by Roberto Firmino and Mohamed Salah. The timing and power of their challenges brought regular roars of approval from the local crowd. Allan was also invited to make a crucial interception on Salah, after a skillful touch by Sadio Mané, almost expelled the Egyptian international from a corner of Napoli. With Fabinho equally impressive in midfield, Liverpool often created the space in which his three front players often wreak havoc. Koulibaly, Kostas Manolas and their fellow defenders had none of that, however, and Alex Meret in Napoli's goal had only one defense to be defended in the first half. This resulted in Insigne losing the ball to Jordan Henderson within his own area. Henderson threw Mané to the left, but Meret defended the attacker's low kick with his legs.
Adrián, who made his first Champions League appearance of his career at the age of 32, had already made a good double defense to prevent Fabián Ruiz from leading the home team to the lead.
The Liverpool goalkeeper deflected the powerful midfield kick to the full extent and repeated the trick as the rebound gave Fabián a second bite. Lozano returned home after Adrian's second defense but was clearly prevented and his celebrations lasted correctly.
Fabián received another opportunity from one of Mertens' many inviting crosses, but kicked back through the goal and got in the way of Van Dijk when the shot was given. Another cross from Mertens on the right seemed destined for Insigne's head only for Joël Matip to intervene with a vital touch.
The game continued to flow both ways. James Milner flew over after Salah escaped Koulibaly's attention for the first time and led the midfield into the area. Milner almost returned the favor when Liverpool dangerously broke Henderson and Mané, but with Salah hidden unmarked at the post, his low cross was cut off by Mário Rui's slip. Firmino headed the subsequent corner of Salah, which was pushed aside.
Neapolitan heads were at hand early in the second half after Adrian made a spectacular save to prevent Mertens from advancing. Liverpool stayed open when Insigne threw Mario Rui from the left – Alexander-Arnold received little protection all night – and the defender made a wonderful cross for the post that prevented Van Dijk and Mertens from meeting a volley. The Belgian international was imagining his goal celebration when Adrian somehow dropped a shot that was destined for the top corner at close range. Mertens was left in disbelief.
Liverpool should have capitalized when Mané defeated Insigne in a Napoli corner kick and led to a two-by-one break in the middle of the house. Salah was begging for the ball inside. Mane delayed, delayed and eventually replaced the pass on his unmarked teammate. Unlike Burnley, Mané was apologizing this time. Salah had a chance to beat Meret moments later when Manolas missed an attempt to clear Koulibaly's header.
The ball fell invitingly to Salah, who kicked his left foot towards the bottom corner, only for the Napoli goalkeeper to make an excellent save on his toes.
Ancelotti sought an answer, introducing Piotr Zielinski to Insigne and a chorus of boos from the local crowd, the former Tottenham Llorente striker for Lozano, with the Spanish striker giving the last word in the 90th minute.