Group 8 winners Portugal maintained their perfect record in the section with a 2-1 victory in Drammen.
The visitors stamped the authority that had underpinned their qualification campaign on the first half of the game and took the lead after 22 minutes when Carlos Mané was played through on the left-hand side and finished confidently.
Norway were a different proposition after the interval but suffered a decisive setback when Portugal doubled their lead after 62 minutes, substitute Ricardo receiving a pass in the area and keeping his composure. Norway deservedly pulled one back swiftly through Mushaga Bakenga but could not force an equaliser, despite the impressive promptings of 15-year-old Martin Ødegaard.
Portugal complete their qualifying phase matches at home to Azerbaijan on Tuesday before taking their place in the play-offs.