Napoli prepared for its midweek clash against Inter Milan by beating struggler Spal only 1-0 in Serie A on Saturday.
Raul Albiol headed in during first-half stoppage time as Napoli dominated to such an extent that the score flattered Spal.
Napoli moved to within five points of league leader Juventus, which hosted Roma later.
Second-placed Napoli also moved nine points ahead of Inter, which was also playing later against bottom club Chievo Verona.
Napoli visits Inter on Wednesday.
Napoli dominated and thought it took an early lead but Lorenzo Insigne’s effort was ruled out for offside.