Playing four matches and collecting twelve points is no coincidence, but rather the coach's excellent preparation. Although their Champions League performance was a bit disappointing after their defeat to Manchester City, Napoli's overall strength is much stronger because they have a number of experienced players, and now it's up to the coach to combine the strengths of his players.
The upcoming match will be a bit more difficult and challenging, as Napoli will face AC Milan, and the match will be at AC Milan's home ground, making things a bit more difficult for Napoli. A defeat could impact their standings, as Juventus will face a much easier opponent in the next match.
Napoli started well by winning all four matches in the league, but to be honest, I don't expect anything less from them. Aside from Florentina, the rest opponents they went up against were mid or bottom table clubs and I expected a win. Their real strength will be tested in their upcoming matches. If they can be able to win strong opponents like AC Milan and the likes, then I'm sure they'll do well this season.