What is this?
These are the final play-offs to determine the last nine countries to qualify for Russia 2018.
Which teams have secured their World Cup place?
So far 23 teams are assured of their place in Russia next summer without the need for play-offs. They are:
Europe: Belgium, England, France, Germany, Iceland, Poland, Portugal, Russia, Serbia, Spain
South America: Argentina, Brazil, Colombia, Uruguay
Asia: Iran, Japan, Saudi Arabia, South Korea
North, Central America and Caribbean: Costa Rica, Mexico and Panama
Africa: Egypt, Nigeria
What are the remaining matches?
Africa is the only Fifa confederation yet to finish the group stage of its qualification process. Nigeria and Egypt are the two African nations already guaranteed a World Cup place, but three more spots are up for grabs and there are eight nations still in the hunt.
Those remaining group stage matches will take place between November 10 and 14. African teams do not take part in any play-offs, so all will be decided by the final group placings.
The fourth-placed team from North, Central America and Caribbean qualifying will play the winners of the Asian qualifying play-off for one spot at the World Cup.
Honduras finished fourth and Australia saw off Syria in the Asian play-off, with the two teams now due to face each other over two legs on November 6 and 14.
The other inter-confederation play-off sees the winner of the Oceania qualifying play-off face the fifth-place team from South America.
New Zealand thrashed Solomon Islands in the Oceania play-off, which means they face Peru over two legs on November 6 and 14.
With the group stage done and dusted, there are eight second-placed teams (Slovakia are the unlucky losers who failed to make the cut) that now advance to the play-offs to determine the final four European teams making it to Russia next year.
They are: Switzerland, Italy, Denmark, Croatia, Sweden, Northern Ireland, Greece and Ireland.
The eight teams will be split according to the Fifa world rankings, which will determine four seeded teams to be drawn against one of the four unseeded teams.
The seedings will be:
Seeded: Switzerland, Italy, Croatia, Denmark
Unseeded: Northern Ireland, Sweden, Republic of Ireland, Greece
When will the European play-off draw take place?
The updated Fifa rankings will be officially published on October 16, with the European play-off draw taking place the following day (October 17) in Zurich at 2pm BST.
The first legs will be played from November 9 to 11 and the second legs between November 12 to 14.