Mario Pašalić and Robin Gosens scored in the second half to extend Atalanta’s club record tally to 82 league goals this season, in 29 matches.
It was Atalanta’s seventh successive Serie A win and saw Gian Piero Gasperini’s team move back to within four points of Inter, which beat Brescia 6-0 on Wednesday.
It halted a run of five straight league wins for Napoli, which also won the Italian Cup last month.
Despite it being a meeting between two of the in-form teams in Serie A, chances were few and far between in the first half.
Napoli goalkeeper David Ospina was forced off with an injury after clattering into his own teammate. He was replaced by Alex Meret.
Meret was let down by his defense three minutes into the second half when they left Pašalić unmarked to head in a cross from Alejandro “Papu” Gómez.
Atalanta doubled its lead eight minutes later as it counterattacked rapidly before spreading the ball from right to left in the penalty area for Gosens to finish off with a diagonal shot into the bottom right corner.
Arkadiusz Milik had a goal ruled out for Atalanta for offside late on.
Source: Fox Sports