Walter Mazzari, the Napoli head coach, noted the significant anniversary. "It has been 21 years since Napoli played in the European Cup, so we have some catching up do."
By that token, Manchester City have even more time to make up. The last and only time City competed in club football's most elite competition was 1968.
In 1990, Napoli lasted two rounds, eliminated by Spartak Moscow. The European Cup has changed greatly since then, taken on its new name, the Champions League, and become a great deal more demanding of time and resources, which is why City have built up such an abundant squad for this particular challenge, and why Napoli rested key players for their 3-1 win at Cesena at the weekend.
The last time Napoli entered the European Cup, squads containing 22 internationals were not the order of the day. Indeed, that Napoli sometimes caricatured as simply a one-man team.
Sure, they had admired footballers like the Brazilians Careca and Alemao, and Italian internationals like Fernando De Napoli and Andrea Carnevale but the inspiration in a period that yielded two scudettos, Serie A titles, and a Uefa Cup triumph was the squat figure of Diego Maradona.
In Naples, Maradona still casts such a shadow from that glorious phase that even a generation later, it manages to loom even over Napoli's return to the upper rung of European football.
The fact that Sergio Aguero, father of Maradona's first grandchild, is involved in the first Napoli fixture in the Champions League seems somewhat fateful.
The coincidences extend. Maradona's final match for Napoli, in the spring of 1991, was a Serie A defeat against Sampdoria. In the Sampdoria team, one about to displace Napoli as domestic champions, that day was one Roberto Mancini, then 26.
"I was young, so it was an important time for me, up against a Napoli at their best moment, when Maradona played, when they were in the European Cup," Mancini, now manager of City, told reporters ahead of tonight's game.
Asked about the scorer of Napoli's only goal in that 4-1 Sampdoria win, he said, with an ironic smile: "Maradona? He wasn't too bad."
Napoli include individuals with whom Mancini has crossed paths before. Paolo Cannavaro, the Napoli captain, had begun his playing career, with Parma in Serie A, when Mancini was still active, in his 30s, as a player for Lazio.
Goran Pandev, the 29-year-old striker signed by Napoli from Inter Milan this summer, was transferred to Lazio when he was 20, while Mancini was head coach at the Rome club.
It is a barely disguised secret that City had been interested until recently in whether Edinson Cavani, the scorer of 26 Serie A goals last season, might be available for transfer. Once they had recruited Aguero, that interest faded. Mancini sees the chief threat coming from Napoli's talented attack.
"This Napoli is a good team … " said the City manager. "And they have fantastic supporters." Many of those who have travelled to Manchester have waited a whole generation for this sort of trip.