On Monday Naples celebrates its patron saint, Gennaro, whose 1,700-year-old old blood will be produced in a vial by the Catholic church for its thrice-annual liquefaction "miracle" – in which it transforms mysteriously from a dried state back into a liquid, and then back into a solid once more. But on Sunday evening the city was toasting an even more remarkable sight. It's not three times a year that you get to see your team clobber the reigning champions.

"Edinson … Edinson … Edinson …" cried the increasingly hoarse public announcer at the Stadio San Paolo, so lost in the moment that he even failed to do his usual job of firing up late 90s pop-dance number Samba de Janeiro. "Cavani! Cavani! Cavani!" came back the cry from the near 60,000 crowd. It is a familiar routine these days, but even by the standards of Serie A's most boisterous supporters this had a hint of added delirium. Fresh from his Champions League goal against Manchester City, Edinson Cavani had just stuck his third of the night past Milan's Christian Abbiati.

Hat-tricks are hardly unfamiliar territory for Cavani, whose 26 league goals last season included trebles against Lazio, Juventus and Sampdoria, but this was still that little bit more special. Milan, after all, last year boasted the most miserly defence in the entire division. And as if that wasn't enough, all three of the goals had been really rather wonderful.

The last was the pick of the bunch – volleyed instinctively into the corner despite having arrived at his feet in the blink of an eye after Ezequiel Lavezzi's cross deflected off Alessandro Nesta – but the other two weren't bad either. The first had also been volley – crashed through Abbiati's legs following a header across goal from Lavezzi – while the second was the fruit of a classic Napoli counterattack, lashed in by Cavani at the near post following a marauding 60-yard run by Walter Gargano.

Corriere dello Sport would pronounce him "King Cavani" on Monday morning, though there are those in Naples who believe sainthood would be more appropriate. Certainly the city's Archbishop Crescenzio Sepe has claimed divine intervention on the player's behalf before, saying "God serves himself by having Cavani score goals" before suggesting the deity had "helped" in last year's rout of Juventus. Less religious-minded locals settled last year for creating a calzone in his honour, though the player himself was unimpressed with the choice of fillings for the "Cavani-Matador".

Either way it seemed fitting that he should become the first Serie A player to take home a match ball (well, formally at any rate), following the league's belated introduction of the rule that the scorer of a hat-trick should get to do so. Not that you would ever catch Cavani in self-congratulatory mode. "I want to share this joy, this happiness, with the fans," he said afterwards. "But now we must think about Wednesday, about Chievo, a tricky away game. Was this win a sign for the rest of the league? Maybe, but it's a long season."

It is indeed, though to possess a five-point advantage over fellow pre-season favourites Inter and Milan at such an early stage represents a rare coup. Never before, in fact, have both Milan clubs picked up just a single point each from their opening two league fixtures. The result this weekend was all the more impressive for Napoli given the fact they had a day less to recover than their opponents following their respective involvements in Europe.

But it would be crass to reduce Napoli's victory simply to Cavani's brilliance, when so many others played a part. Gargano, leaving aside his assist, was a model of understated efficiency in the middle, as was his new midfield partner Gokhan Inler – an inspired signing from Udinese in the summer. Morgan De Sanctis, in goal, made a fine save to deny Alberto Aquilani at 2-1 while Lavezzi was a thorn in Milan's side despite still carrying the heel injury suffered against City.

But the real star of the show may have been the manager Walter Mazzarri, sleeves rolled up as ever on the sideline as he surveyed his greatest work. It is his tactics, his commitment to a bold 3-4-2-1, that have allowed Napoli to become the team they are today, his hand that is seen in the team's breathtaking counterattacking style. When Gargano departed on the mad charge that would lead to Cavani's second after 36 minutes, he did so without a moment's hesitation – just as Christian Maggio had in seizing on Gareth Barry's misplaced pass at the Etihad Stadium four nights earlier.

Milan will point to mitigating circumstances of course, to the fact that Kevin-Prince Boateng and Robinho were both unavailable, as was Zlatan Ibrahimovic – last seen shooting elks during a break from his rehab programme in Sweden. Missing, too, were Massimo Ambrosini and Gennaro Gattuso in midfield, while Napoli were fortunate not to have a penalty awarded against them when Paolo Cannavaro appeared to handle in the area shortly after Cavani had made it 3-1.

"This match was an anomaly," insisted the Milan manager, Massimiliano Allegri. "We kept the ball, we went in front. We didn't manage to preserve our lead because the equaliser arrived in a somewhat fortuitous way. Are Napoli the scudetto favourites? The favourites don't change with one match. At the end of the season you will have all the same teams there. Napoli deserve credit because they played the match they had to play and we messed up. But there is no concern on my part."

That is a reasonable enough stance to take so early in the season. But when your opposition have a king and saint-in-waiting on their side, you may not want to give them a head start.

Talking points

• Alexandre Pato didn't get a chance to show off any moves at the weekend, but perhaps that's for the best. "He's unwatchable," declared Thiago Silva after the pair indulged in a quick shimmy at the end of Milan's draw in Barcelona. "In fact, I always say he's not a real Brazilian. To think he listens to hip hop."

• Gian Piero Gasperini remains manager of Inter for now, despite another horribly disjointed Inter performance in their 0-0 draw at home to Roma. As I reflected in the closing notes of my minute-by-minute report, the blame for Inter's present state should lie more with Inter's directors than their manager – but that is not to exonerate a man who seems to lack the courage of his convictions. For the fourth consecutive game (taking into account the pre-season Super Cup) he completely overhauled his tactics, and for the fourth time his players looked lost. The decision to withdraw Diego Forlán for Sulley Muntari with 10 minutes to go said it all. On a more positive note, congratulations to Javier Zanetti for matching Giuseppe Bergomi's record of 756 games in an Inter shirt.

• As for Roma, there were at least some positive signs in the regular link-ups between Francesco Totti and Fabio Borini, but while Luis Enrique is at least set with his 4-3-3 formation there are still too many players underperforming. One chance at the start of the second half aside, Pablo Daniel Osvaldo was anonymous. In better news, Maarten Stekelenburg has been released from hospital, where he had spent the night following his boot to the head from Lucio.

• Did Juventus put in a perfect performance on the way to winning 1-0 in Siena? No. But will their fans care one jot as they survey a league table that shows they too are already five points ahead of both Milan clubs? Hmm. Any club that can leave Milos Krasic, Fabio Quagliarella and Eljero Elia on the bench can't be in too bad a shape.

• Juventus and Napoli aren't the only ones off to perfect starts, but are instead joined at the top by Cagliari and Udinese, after wins over Novara and Fiorentina respectively. Whilst you wouldn't want to infer too much from that for the rest of the season, Cagliari in particular still deserve to enjoy the moment – this is the first time since 1970 that they have opened a Serie A season with consecutive wins.

• Djibril Cissé informed the world this week that he and his new strike partner Miroslav Klose "never stop talking, not even in the shower". In which case the German might want to tell his team-mate at some point that there are more effective routes to goal than taking hopeful pot-shots from 25 yards. A 2-1 defeat at home to a Genoa team with a miserable recent record on its travels was not what was expected from this Lazio side after their draw in Milan. The loss of Stefano Mauri to injury could prove to be a heavy blow.

• Think the pitch at San Siro looked bad at the weekend? Atalanta and Palermo conducted their meeting in the early kick-off on Sunday in a swamp – conditions getting so bad at one point at the Stadio Atleti Azzurri d'Italia that the match had to be halted for 30 minutes. Whether it should have been allowed to continue after that is a matter for debate, but Atalanta will be happy it did after taking three points off their pre-season penalty to move up to -2.

Results: Atalanta 1-0 Palermo, Bologna 0-2 Lecce, Cagliari 2-1 Novara, Catania 1-0 Cesena, Inter 0-0 Roma, Lazio 1-2 Genoa, Napoli 3-1 Milan, Parma 2-1 Chievo, Siena 0-1 Juventus, Udinese 2-0 Fiorentina

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