In front of a raucous home crowd, Portugal wasted little time in giving them something to cheer about, taking the lead after just 95 seconds.
Bernardo Silva dispossessed Nemanja Gudelj on the edge of his own box, with the ball eventually dropping to Renato Sanches to finish.
The goal was reviewed by VAR for Silva’s challenge, and despite Dragan Stojković’s protestations, the goal was awarded and the hosts had the perfect start.
That opener could have proven devastating for Serbia, but they grew into the game after falling behind, and found a leveller shortly after the half-hour mark.
Dušan Tadić’s seemingly innocuous shot was spilled by Rui Patrício into the net, but while the equaliser was a hugely welcome morale boost for Serbia, they still knew nothing but a win would secure qualification.
Duly, they introduced Aleksandar Mitrović for the second half.
Inevitably, the switch opened up spaces on the counter attack, and the hosts exploited this, with Sanches squandering a huge chance to restore the lead.
Not intimidated by Portugal's power and prowess, the Serbians continued to press for a winner.
They found the breakthrough in the 90th minute to stun all of Lisbon into stone-cold silence, as Mitrović made no mistake from a gilt-edged chance, sending a powerful header past Patrício at his near post.
Portugal will now have to go through the play-offs if they are to join Serbia in Qatar next year.
All the hosts needed was a draw to go through automatically, but their first loss of the qualifying campaign proved very costly.
Meanwhile, Serbia’s stunning victory marks their first win over a side in the top 30 of FIFA's world rankings since 2013, and their maiden victory over Portugal on hostile turf.
Source: flashscore
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