Napoli avenged their Coppa Italia defeat to Atalanta with a 1-0 victory in Bergamo.
Dries Mertens settled a tight contest after 65 minutes, accepting Jose Callejon's through ball to fire home an angled drive for his 14th goal of the season.
The win extends Napoli's Serie A lead over Juventus to four points.
Juventus are at home to Genoa on Monday night and the reigning champions might have hoped Atlanta would shock Napoli again after making an impressive start.
Atalanta knocked Napoli out of the Coppa Italia just over two weeks ago, but they were unable to turn pressure into clear-cut chances.
Bryan Cristante spurned Atalanta's best chance from an Alejandro Gomez cross after 20 minutes.
Moments later Lorenzo Insigne saw his volley deflected wide, but Napoli created little until Mertens struck.
Napoli captain Marek Hamsik fired over before his stoppage-time effort was ruled out for offside by the Video Assistant Referee.