The Partenopei missed Dries Mertens, Diego Demme and Faouzi Ghoulam under new boss Luciano Spalletti, while the Lagunari had Marco Modolo, Pasquale Mazzocchi, Antonio Vacca and Mattia Aramu suspended, Domen Crnigoj injured, Gianluca Busio and David Okereke not yet cleared after transfers.
Victor Osimhen twice harassed the Venezia goalkeeper and defence into early errors with his pressing, but was a bit too aggressive when shoving Daan Heymans as they tussled on a corner and the referee opted for a straight red card, considering it to be a punch.
There was even more trouble for the hosts, as Piotr Zielinski pulled up by himself with a suspected thigh strain.
Napoli thought they’d found the breakthrough when Mattia Caldara clumsily used his arm to block a Mario Rui cross in the box. Insigne stepped up, but tried to lob his penalty into the far top corner, missing the target entirely.
However, just four minutes later, Pietro Ceccaroni did exactly the same thing, using his arm to charge down the Giovanni Di Lorenzo cross in the area and this time Insigne kept it simple, sending Maenpaa the wrong way.
Venezia came so close to an equaliser and really should’ve found the net, but Francesco Forte smacked his finish against the upright from a Johnsen pull-back.
Forte couldn’t make the most of another opportunity created by Molinaro, as Kalidou Koulibaly made the decisive sliding tackle.
Napoli 2-0 Venezia
Insigne pen 62 (N), Elmas 72 (N)
Sent off: Osimhen 23 (N)
Missed penalty: Insigne 57 (N)