The Partenopei were fired up after their win away to Milan, which put them in joint second place. Lorenzo Insigne was still out after testing positive for COVID-19, with Victor Osimhen, Kalidou Koulibaly and Fabian Ruiz injured, but Mario Rui returned. Spezia were in dire straits and missed M’Bala Nzola, Daniele Verde and Jacopo Sala.
Piotr Zielinski fired over in the opening minutes, while Rey Manaj’s header skimmed the bar. Matteo Politano cut inside from the right and drilled left-footed inches wide of the near post, while Mertens also fired off target.
Spezia took a shock lead with their first real attack, as a Simone Bastoni free kick grazed the head of Juan Jesus and surprised David Ospina for an own goal.
Zambo Anguissa had penalty appeals waved away for a nudge, but Mario Rui was booked on the stroke of half-time and will be suspended against Juventus.
After the restart, Chucky Lozano’s acrobatic volley went over at the back post. Lozano also had the ball in the net on 54 minutes, but Politano was already offside when making the run for the assist.
Napoli saw another goal disallowed when substitute Andrea Petagna pushed Martin Erlic before the header.
He hosts wasted a golden opportunity on 62 minutes, as Mario Rui pounced on a poor back-pass to set up Lozano, who somehow fired it straight at last man Erlic with the goal gaping.
Lozano again scuffed his finish straight at Ivan Provedel on a Matteo Politano cross, while Mario Rui made a decisive block on Manaj at the back post.
Giovanni Di Lorenzo forced Provedel to parry with a foot on a pull-back from the by-line, while there were timid penalty appeals in stoppages for a high foot on Adam Ounas.
It was a siege, Eljif Elmas towering above the crowd for a header on the Ounas cross that bounced off the crossbar.
Napoli 0-1 Spezia
Juan Jesus og 37 (S)