Shamrock Rovers remain without a point in Europa League Group A after losing to Greek side PAOK Salonika.
Costin Lazar put the home side in front with a right-foot shot from 30 yards in the 12th minute after a poor defensive clearance by the Irish part-timers.
Rovers earned the equaliser their plucky performance deserved when Karl Sheppard headed home from a Billy Dennehy free-kick on 48 minutes.
Vierinha scored the winner with a right-foot strike after 63 minutes.
The Portuguese player fired in from outside the penalty area.
Vierinha had gone close before half-time but his free-kick was saved by Rovers goalkeeper Ryan Thompson.