SERBIA qualified for the World Cup for the second time since becoming an independent nation in 2006 after beating Georgia 1-0 on Monday.
Aleksandar Prijovic's 74th-minute goal in Belgrade ensured Serbia topped the group by two points and was back in soccer's biggest stage for the first time since 2010.
The Serbs took their second chance to secure qualification, after losing in Austria on Friday.
Meanwhile, Ireland won in Wales 1-0 to seal second place and a spot in the playoffs.
At the end of a tense final round of qualifying, Chris Coleman’s Welsh dropped to third place in Group D and was out of contention for a place in next year's tournament in Russia 15 months after reaching the semi-finals of the European Championship.
With Serbia winning, the Celtic showdown between Wales and Ireland in Cardiff was for the prize of a play-off spot in November.
Ireland took it, thanks to James McClean's 57th-minute goal following a defensive mix-up by the Welsh.
The Irish are looking to qualify for the World Cup for a fourth time and first since 2002.
They will not be seeded in the playoffs draw, which takes place on Tuesday.
Gareth Bale, the Real Madrid star, missed the game because of injury.