Gennaro Gattuso's side moved a point ahead of Atalanta and AC Milan, with Juventus four points further back.

Those three teams play on Wednesday before the final two rounds of the campaign.

The top four from Serie A qualify for next season's Champions League.

Napoli dominated from the start and Piotr Zielinski opened the scoring in the 28th minute, firing home a rebound, before setting up a second for Fabian Ruiz three minutes later.

Stefano Okaka pulled one back for mid-table Udinese shortly before halftime but Hirving Lozano and Giovanni Di Lorenzo extended Napoli's advantage after the break.

Napoli captain Lorenzo Insigne hit the woodwork late on but got his goal in stoppage time as he controlled an attempted clearance with his chest before firing powerfully into the bottom corner.

Australian Associated Press