Northern Ireland's impressive start to the qualifiers was brought to a halt after a 2-0 loss to Romania in Bucharest.
Two Paul Papp goals in the second half were enough to bring the North's run to a close.
Also in Group F, minnows the Faroe Islands shocked Greece 1-0 in Athens while Hungary beat Finland by the same margin.
The night's results put Romania top of the group, with Northern Ireland a point behind in second. Major tournament regulars Greece prop up that group with one point.
And in Group I, Cristiano Ronaldo scored late to give Portugal a 1-0 win over Armenia while Denmark came from behind to beat Serbia 3-1.