The Belgian curled in from the edge of the box in the Stadio San Paolo to join his former team-mate at the top of the chart.
Dries Mertens became the joint-top goalscorer at Napoli’s history when he found the net from Barcelona on Tuesday.
The attacker netted the first goal of the Champions League last-16 first leg against the side when he took on a Piotr Zielinski cut-back on the edge of the box and sent it curling past goalkeeper Marc-Andre ter Stegen and in the top corner.
It was the 32-year-old’s 121st target for the Serie A side and puts him top of the all-time scoring charts alongside former captain Marek Hamsik.
Mertens needed just 310 looks to join his former team-mate on top, whereas Hamsik needed over 500 matches to achieve the tally.
The pair are just six goals before Argentine star Diego Maradonna, who spent seven years in Napoli and won two Serie A titles and a UEFA Cup.
Mertens moved into the Stadio San Paolo from PSV in 2013 and netted 13 times in 47 games in his debut season as they won the Coppa Italia.
However, the Belgium global’s real breakthrough in Italy came in 2016-17 when he completed the campaign with 34 goals in all competitions.
This season, Mertens has 12 goals from 28 matches for a group sitting in the Italian top-flight – six points behind fifth-placed Roma and 24 adrift of defending champions and leaders Juventus.
The prior Utrecht celebrity’s time at Napoli could be nearing an end, but as his contract will expire at the end of the season.
Although Napoli are thought to be attempting to tie him down to a new deal, reports in Italy have connected him with a summer move to Inter and other clubs are expected to go into the frame.
Chelsea made an enquiry over the prospect of signing him close to the end of the January transfer window as they appeared to bring in a new striker but the Serie A team refused to let him go.