For a team that completely renovated its squad during the summer, the chemistry Rafael Benitez's men have shown so far is astounding.
Without further ado, here are five things we learned from this pivotal Champions League group stage fixture:
Gonzalo Higuain is showing the Partenopei faithful that he's hardly a drop-off from Edinson Cavani.
The former Real Madrid striker and Argentine national team starter joined Napoli to fill up the massive boots left by El Matador, and has impressed so far, linking up well with teammates and giving Napoli an experienced center forward to lead the frontline.
He has repaid owner Aurelio De Laurentiis' trust, scoring two domestic goals and an important header against Borussia Dortmund which put Napoli 1-0 up against the German outfit.
Group F is probably the most balanced of them all, with Arsenal getting all three points from their home match against Marseille.
This current Napoli squad still wasn't tested by truly gifted opposition, but the match against Borussia Dortmund showed that they can go toe-to-toe with anyone in Europe.
Arsenal's quick, technical attack will give Napoli's defense another headache. More on this in the next slide:
Anyone who has watched Napoli this season will tell you that their Achilles' Heel is at the back.
The makeshift four-man defense includes the two wingbacks Christian Maggio and Javier Zuniga, who are at their best when they're in a more offensive role.
The risk with this formation is that Maggio and Zuniga have shown through the years that they're much more adept at playing in a 3-5-2, where they are more free to venture forward.
In the center, Raul Albiol should start alongside captain Paolo Cannavaro, who has been preferred at times to Miguel Britos by coach Benitez.
It will be interesting to see how they'll deal with top-class strikers as the tournament continues.
Rafael Benitez was given a second chance in Italy after his first outing with Inter was worth forgetting.
De Laurentiis gave Rafa Benitez the ability to suggest freely in the Summer transfer window and buy players that would fit his style, which switched Napoli's familiar 3-5-2 under Walter Mazzarri to a more conventional 4-3-3.
Napoli will be riding high on confidence before they encounter Milan this weekend in Serie A.
The diminutive 22-year-old Lorenzo Insigne is showing more and more flashes of the brilliance which led his hometown team to bring him back after a stellar season at Pescara in Serie B.
Now in his second year at Napoli, the tricky Insigne has gotten a bigger role from Rafa Benitez, and paid back the Spanish coach with a world class curling free kick to give Napoli a 2-0 lead over Borussia Dortmund.
His creative ability and eye for goal make Insigne one of the hottest prospects in Italy, and one who will test plenty of teams in the Champions League.