Wales host Bosnia and Herzegovina in the World Cup play-off semi-finals, while Scotland are at home to Austria.
A win in Wales would earn them a trip to face Switzerland in one of the three play-off finals.
Should Scotland beat Austria, they will again be at home in the final against the Republic of Ireland.
The play-offs will decide two automatic qualifiers for the 2023 World Cup plus one country to play in an inter-confederation play-off.
Wales secured second place in their group with Tuesday’s 0-0 draw against Slovenia and are possibly two wins away from their first World Cup finals.
Scotland were runners-up to Spain in Group B.
They got ready for the playoffs with a six-goal thrashing of the Faroe Islands in their final qualifier.
The two UK nations join seven other second-placed teams in the European play-offs.
The top three – Iceland, Republic of Ireland and Switzerland – go straight to the one-legged play-off finals on 11 October.
Wales and Scotland must win their one-legged semi-finals on October 6 to reach their respective finals.
Portugal will host Belgium in the third semi-final, with the winners at home to Iceland in the final.
The two best-ranked eventual winners – based on performance in their qualifying groups and play-off finals – will head to the World Cup, with the third-placed team going to the inter-confederation play-offs next February in New Zealand.
These playoffs will feature 10 teams divided into three legs, with three World Cup spots on offer.
The third European play-off winner will play one of Chinese Taipei, Thailand, Cameroon, Senegal, Haiti, Panama, Chile, Paraguay and Papua New Guinea in a final.
Scotland reached their first World Cup final in 2019 but missed out on this summer’s European Championship after finishing behind Finland and Portugal in their qualifying group.
According to the FIFA world rankings, Iceland, at 14th, are the strongest team participating in the European play-offs, ahead of Belgium, who are 19th.
Austria is in 20th place and Switzerland is 21st with Scotland, which is 23rd, following. The Republic of Ireland is in 26th place, with Portugal 27th and Wales 30th, while Bosnia and Herzegovina is 63rd.
World Cup playoffs – how do they work?
- The nine teams that finished second in the qualifying groups are given a play-off spot.
- The play-offs consist of a semi-final and a final, both one-legged ties.
- The matches will be held on Thursday 6 October and Tuesday 11 October.
- Based on performances in the qualifiers, the top three teams – Iceland, Republic of Ireland and Switzerland – receive a bye to the final, while the remaining six teams will enter the semi-final draw.
- The three winners of the semi-finals will play in the final against one of Iceland, the Republic of Ireland or Switzerland.
- Of the three final winners, the two highest-scoring teams will qualify for the 2023 Women’s World Cup.
- The third team will participate in a play-off between the Confederations, which will be held in New Zealand in February 2023.