First of all, I ain't a dude.
Second of all, ain't no way you can compare our team with Spanish. And no matter how "weak" you say they are, you can expect them to win against anyone.
And third of all, if you actually knew something about our national team you'd know how much of a mess it was in the past decade. The way you described Portugal is what we were in that period of time. A bunch of good players losing against Estonia, Slovenia, Macedonia, Honduras, Australia, humiliated by Ukraine (5-0), Denmark... and other average or below average teams (with all due respect to those nations). Empty stadiums and basically no expectations at all that we can win against even average oponnents.
With Stojkovic all of that changed, starting from the atmosphere around the team, their cohesion, relations between the players and finally, the way they play. Now I go into the game expecting a win, doesn't matter if we play against San Marino or Portugal.
So to draw the line, Serbian football fans have suffered a lot in the past; let us rejoice now. lol