Well, who saw this coming? If you'd have told us at the start of the game, that one of Napoli and Atalanta would be leading 4-0 at half-time, we wouldn't have been too surprised.
That's mainly because Atalanta can put four goals past any team in Europe if they fancy. What we didn't expect, was that it would be Gennaro Gattuso's men blowing their opponents away on Saturday afternoon.
This battle was seen as an acid test for both teams. I Partenopei had won their opening two matches, scoring eight and conceding none, while la Dea had scored four, four and five in their three outings. Bang in form.
The duo were viewed as certain top-four candidates before a ball had been kicked in the 2020/21 campaign, while a crack at a title charge wouldn't stretch the realms of the imagination too much. Saying that, the hosts didn't even threaten the top six last year. But their end of season form - plus a Coppa Italia success - created a platform on which they have continued to build.
Now, those sneaky suspicions are much more concrete than a month ago. Napoli have been simply brilliant since the season got underway. Defensively, the Italian giants have cut out the silly mistakes that plagued them during the final months of Carlo Ancelotti's reign this time last year, and it comes as no surprise that a team coached by Gattuso is organised, resolute, and a keen collector of clean sheets.
And a centre-back partnership of Kalidou Koulibaly and Kostas Manolas shouldn't be shipping too many chances, anyway. It's at the other end of the pitch where we've seen a dramatic improvement since the Italian coach's arrival. His teams have often been stodgy in the final third, relying on their strong backline to get them through matches.
Not this time, though.
This Napoli side is fast, in sync and frankly, pretty sexy.
Gattuso has gambled on his attacking stars obliterating their opponents from the off, setting up an offensive formation with a ruthless and relentless forward line. I Partenopei started the game with Hirving Lozano, Dries Mertens, Mateo Politano and Victor Osimhen all on the pitch, and it worked to devastating effect.
The quartet linked up like a squad of synchronised swimmers, reading each other's next move with supernatural ease, and knowing exactly which space their teammates would attack next. First on the scoresheet was Lozano, a man of whom much was expected last season, but he ultimately failed to live up to the hype.
Perhaps Gattuso lacked faith in the Mexican to replace the ever-consistent Jose Callejon, and although he may occasionally be a miss rather than a hit, his electric highs are so much more exciting than those of his predecessor.
The four forwards have adapted to the Neapolitan tradition of being flexible in attack, able to pop up on either flank or centrally to cause problems. This liquid movement led to the opening goal of the game against Atalanta, when the visitors simply couldn't keep up or compete with their constant fluidity.
Another promising aspect from Saturday's eventual 4-1 victory was Victor Osimhen opening his account for the club. Having arrived from Lille in a deal worth up to €80m, hopes were sky high for the Nigerian hitman.
The 21-year-old was a revelation in pre-season, hitting hat-tricks for fun in his exhibition outings. And although he had impressed when given the chance in the league, the end product was clearly missing from his performances.
Those fears have been put to bed, after Osimhen clinically buried his chance on 43 minutes, adding the fourth to Napoli's incredible first-half display. The haul came in a blistering 20 minute burst, knocking Atalanta onto the canvas, from which they struggled to recover.
The second half was as routine as 45 minutes of football can be, with Gattuso's men sitting back and allowing their wounded opponents to run at them. Gian Piero Gasperini's side did score (of course they did), but they only managed to breach the defence once, with David Ospina, Manolas and Koulibaly all sticking to their task manfully.
As far as dream performances go, Napoli supporters couldn't have asked for much more. The win puts I Partenopei a point behind Milan and Atalanta at the top of the table - a point which was snatched from them in controversial fashion by the Italian FA, after failing to travel to their huge match with Juventus.
Other than that minor bureaucratic blotch, the notebook is clean as a whistle. Had they faced I Bianconeri before the international break, we may have been offered a better indication of just what this Napoli side is made of - but we've already got a pretty good idea.
Brace yourself. This team may just be the real deal.