The final UEFA participants in the World Cup were decided during the November international window, with four keenly contested ties taking place.
Remarkably, the play-offs sequence saw the elimination of four-time World Cup winners Italy, who miss out on the tournament for the first time in 60 years.
Goal has your complete guide to UEFA's upcoming final qualification fixtures.
PLAY-OFFS FIXTURES & RESULTS
|Team||Agg.||Team||Leg 1||Leg 2|
|Denmark||5-1||Republic of Ireland||0-0||1-5|
The draw for the European play-offs took place on October 17.
It was a seeded draw, with Switzerland, Croatia, Denmark and Italy placed in one pot based on their position in the FIFA world rankings and Northern Ireland, Greece, the Republic of Ireland and Sweden going in the other.
Northern Ireland, Croatia, Denmark and Sweden played at home first, with games taking place between November 9 and November 14.
The specific dates and results, including links to reports, can be seen in the table above.
WHAT ARE THE SECOND-PLACE PLAY-OFFS?
The second-place play-offs - known officially as UEFA's second round of World Cup qualifying - are used to allocate the last four of Europe's 13 places at the finals.
Nine European teams qualify directly as the winners of their first-round qualification groups.
The runners up in those groups are then ranked by points and, if needed, a number of tiebreakers, with their results against the last-placed team in their group discarded.
This was due to the fact that two groups were originally going to have only five teams instead of six. In the end, Kosovo and Gibraltar joined UEFA to round out the groups, but the rules were not changed.
The top-eight runners up qualify for the play-offs - with the ninth missing out - where they are drawn against another team and will play home and away over two legs for a place at the World Cup finals.
This year's draw was seeded, with the teams split into two pots according to their position in FIFA's world rankings.
This year, UEFA will also have a 14th team at the finals because Russia have already qualified as hosts.
WHEN ARE THE PLAY-OFFS?
The play-offs took place during the November 2017 international window.
The first legs were played between November 9 and 11 and the second legs will be played between November 12 and 14.
HOW CAN I WATCH THE PLAY-OFFS?
In the UK, all of the play-off matches were broadcast on Sky Sports Football and could be streamed via Sky Go.
In the US, the Republic of Ireland-Denmark and Italy-Sweden ties were broadcast on FS1 and FS2 and available to streamed via Fox Sports Go.
THE SECOND-PLACE RANKINGS
|8||Republic of Ireland||8||3||4||1||7||5||+2||13|
Above is the final ranking of second-placed teams from the first round.
Slovakia finished as the worst runners-up, and were therefore eliminated. The other eight teams enter the play-offs.
As mentioned, Switzerland, Italy, Denmark and Croatia are the seeded teams based on the latest (October 16) FIFA world rankings.
That means those four teams went into one pot to be drawn against Sweden, Northern Ireland, the Republic of Ireland and Greece.