Marek Hamsik's first goal of the season put Carlo Ancelotti's free-flowing side on its way after 11 minutes, and Dries Mertens bagged a brace either side of half-time to put the game beyond Red Star.

El Fardou Ben pulled one back but Vladan Milojevic's men can no longer progress in the competition after taking just four points from its five games, while Napoli needs just a point in its final game against Liverpool to make certain of its progression.

That point will not come easy at Anfield but Ancelotti will be confident after seeing the Partenopei extend its unbeaten run to 10 matches in all competitions with a fluent display of passing football and clinical finishing.

Napoli's attack found its rhythm quickly and Mertens went close with an audacious behind-the-leg shot before Hamsik connected with Nikola Maksimovic's flick-on at a corner to score with a side-footed volley from point-blank range.

Veljko Simic should have done better when Marko Marin put him through after 22 minutes but David Ospina made a simple low save and the Red Star winger was made to rue his missed opportunity when Mertens beat Milan Borjan at his near post, guiding Fabian Ruiz's deflected cross home with the outside of his right boot.

The second half was seven minutes old when Hamsik's chipped ball forward found Mertens, who controlled it immaculately before curling the ball towards goal with so much power that it went through Borjan's hands and into the top left corner of the net.

Ben's consolation strike was all about Marin, who twisted and turned his way through Napoli's defence to tee up a simple low finish for the Comorian striker, before Napoli weathered a late spell of possession for the visitors as all three points stayed at the San Paolo.