Nani's early goal has put Portugal on course to round off their Euro 2016 qualifying campaign in style away to Serbia.
The Seleccao were ahead inside five minutes in Belgrade after Danny skipped through the home side's defence and despite his effort being saved by Vladimir Stojkovic, Nani was on hand to tuck away the rebound.
Serbia tried to respond on 20 minutes when Adem Ljajic's cross found the head of Aleksandar Mitrovic, only for the Newcastle United frontman to nod his effort over the bar.
The hosts continued to press for an equaliser, with Aleksandar Kolarov drilling a cross into the path of Zoran Tosic, but the forward failed to connect.
On 32 minutes, Nenad Tomovic raced down the right flank and managed to deliver a menacing ball into the box. However, Dusan Tadic's attempted strike failed to hit anything but fresh air.
After Tosic struck a shot straight at Rui Patricio, Ljajic again went close to levelling when his effort brought another save out of the Portugal stopper.
Mitrovic then thought he had a case for a penalty after going to ground in the box before the Newcastle striker wasted another opportunity just before half time as Portugal managed to hang on to their lead.