The scene had been set almost perfectly, which is not something you can ordinarily say about Italian football. This was a big Monday night match - itself, a break from tradition - at the most imposing ground in the country, which was a full house for the first time in weeks, sparing us the depressingly familiar sight of sparsely populated stands. And the top two sides in the country, Milan and Napoli, although Inter had sneaked into second place 24 hours earlier by virtue of their win at Sampdoria.
All the ingredients were there, then, including a robust dose of hype, aided by Sky Italia's decision to run a countdown clock in the top right corner of the screen since mid-morning, and the customary stereotypes about the North v South clash were in place too.
All expectations of a memorable clash, a live advertisement for Italian football like so many entertaining matches this season, though, were dashed. What a dud this proved.
Napoli may have brought with them thousands of fans, as is their custom wherever they play, but they forgot to pack the single most important element that had lifted them to second place: their 'A' game. The type of fast, fluid, exciting football that had insiders and neutrals gushing over the way coach Walter Mazzarri had shaped the side in little over a year.
Milan's 3-0 win, which now gives them a 5-point cushion over Inter while doubling their gap over Napoli, came at the end of a scrappy, syncopated affair which only took off, from the standpoint of goalscoring chances, only after the Rossoneri had taken the lead following a disputed penalty four minutes into the second half.
Referee Gianluca Rocchi did stick to the rulebook in awarding it after Napoli defender Salvatore Aronica had indeed handled the ball while trying to prevent Pato from keeping a loose ball in play, but clumsiness played as much a part in it as intent and it was not the sort of infraction you immediately jump out of your seat for. In fact, it took TV viewers several replays to correctly spot it, and few inside the San Siro had any idea of what Rocchi had just seen.
Once Zlatan Ibrahimovic scored, you sensed Napoli would struggle to strike back. Edinson Cavani, who fills the role of lone striker in his side's quirky but usually effective 3-4-2-1, was never a factor despite being in the best form of his career, but much of his ineffectiveness stemmed from a poor ball distribution that left him starving for service.
Napoli had their usual share of crosses, 28, but none of them was dangerous enough for the well-placed Milan rearguard, at its best in the middle with Alessandro Nesta and Thiago Silva, and even the return of Marek Jankulovski 10 months after his last start at left back was not exploited by Napoli; in fact, the Czech played much better than anticipated and was given an ovation when he left the pitch after 72 minutes, the crowd acknowledging his contribution in limiting tricky wing-back Christian Maggio away from dangerous positions.
Napoli's strength usually lies plugging all defensive holes by defending in numbers then springing forward in waves and trying to position their best players, Ezequiel Lavezzi and Marek Hamsik, who play just behind Cavani, in one-on-one situations. Lavezzi, though, was suspended for the Milan match and his replacement, veteran Giuseppe Mascara, does not possess the lower-body strength - an underrated element of Lavezzi's talent - to keep possession and beat his opponent while challenged from close quarters. The lack of a midfield passer who can open up opportunities from nothing, a very well-known part of Mazzarri's football philosophy, means that once the side loses its flow there are fewer options, and that's what happened at the San Siro.
With Andrea Pirlo still out, Milan did not have much discernible quality in midfield, either. The trio of Gennaro Gattuso, Mark Van Bommel and Mathieu Flamini, while providing an effective barrier in the middle which helped stifle Napoli and their runners, cannot be asked to create on a consistent - or even sporadic - basis. Milan's advantage over Napoli on the evening was their use of Robinho then Kevin Prince-Boateng as a trequartista.
Coach Max Allegri differs from his predecessors Carlo Ancelotti and Leonardo and their patient approach, and wants his players to be more direct, getting the ball forward as soon as possible; when neither Pirlo nor Clarence Seedorf are on the pitch, the side's best players with the ball at their feet are Robinho, Ibrahimovic and Thiago Silva, so it makes sense that a direct connection be created between them.
Robinho, actually did not have of his best games, but his constant movement and interaction with Ibrahimovic and Pato, who's come back stronger from a variety of injuries, helped keep the Napoli defense on their toes.
None of this would have mattered, perhaps, had not Milan broken the deadlock with that penalty. Once the floodgates opened, Allegri's excellent decision to send in Boateng sealed Napoli's fate. The Ghanaian was a revelation for much December, but had been sidelined since the turn of the year and it's safe to say Allegri will again use him in the position once he is fit to start. The goal he scored against Napoli from close range was very similar to the ones he had scored at Bologna and against Brescia, timing his run perfectly on the near post.
Timing was something Napoli failed to show all night. It could be argued they again did not perform on the big stage - they are 0-4 this season against the Milan sides, including in the Coppa Italla - but the truth is they're having an excellent season which has so far gone beyond expectations, and should not be ashamed of one bad performance.
They're building a side that will contend for the title and in fact they're not out of it this season, either. Trailing Milan - who have a more difficult schedule - by six points means little in the 3-points-for-a-win era, and it could be matches against the lower sides that end up making the difference in May.
Doom and gloom after a bad night at the San Siro may be justified, but they should stop and be turned into motivation for the upcoming matches: that, after all, may be a sign Napoli are maturing faster than their pale performance on Monday showed.