Promotion, relegation and the trophy are not the only things up for grabs in the final round of Nations League games, with potential impacts on 2026 World Cup qualifying.
BBC Sport looks at what England, Scotland, Wales and Northern Ireland have to play for in the Nations League itself – and how it ties into the next World Cup.
The World Cup play-offs
Four teams will qualify for a play-off to reach the World Cup via the Nations League.
They are the four best-ranked group winners who do not go on to finish in the top two of their World Cup qualifying group next year.
With teams in the top Nations League division highly likely to qualify for the World Cup through European qualifying – and many teams in the second tier too – it gives an extra incentive for teams across Leagues B and C.
If England finish top of Group B2 or Wales in B4, they would be extremely likely to have a World Cup play-off spot banked.
Northern Ireland currently top C3, which would give them at least a chance.
Scotland, bottom of A1, are not in the running to get a play-off spot through the Nations League.
The four teams who get into the play-offs via the Nations League will be put in with the 12 teams who finish second in their World Cup qualifying groups – with four spots for 2026 up for grabs.
Bigger or smaller World Cup groups
There will be 16 European nations at the expanded 2026 World Cup in the United States, Canada and Mexico – meaning qualifying will look different to before.
There will be 12 groups, containing either four or five teams each, drawn on 13 December.
This will not affect any of the UK nations, but the teams who finish in the top two in each group in League A will go into a World Cup qualifying group containing four teams.
Any team in the various Nations League promotion-relegation play-offs in March will not start World Cup qualifying until June, or possibly September.
Will it make a difference for seedings?
Seedings for the World Cup qualifying groups will largely be decided by Fifa world rankings – and not Nations League finishes.
The exception is that the top seeds will be drawn out of the teams who finish in the top two of each League A group – plus the four top countries by world rankings.
England’s world ranking of fourth, third in Europe, means they are highly likely to be top seeds despite not being in League A.
Who’s going up or down?
All of the home nations have something on the line with two games to go, although the format of the tournament makes that almost inevitable.
Every position above third spot in League C groups guarantees either promotion, relegation, a promotion-relegation play-off or a place in the quarter-finals.
Scotland are close to relegation from League A, sitting bottom by three points before their final games against Croatia and Poland.
England have to beat Greece to have a chance of automatic promotion from League B, or else the best they can achieve is a promotion-relegation play-off with a third-placed team from League A.
Their second game is against the Republic of Ireland, who are three points above Finland and hoping to go into a relegation-promotion play-off.
Wales would win automatic promotion to League A if they beat Turkey and Iceland – but could also be drawn into a relegation-promotion play-off.
Northern Ireland are in an automatic promotion spot in League C and will go up if they win their final two games against Belarus and Luxembourg. They could be promoted with a game to spare if they beat Belarus and Bulgaria do not win.