What do England need to do to win the Nations League? Everything you need to know before the match against Croatia

England's final UEFA Nations League group game is just around the corner - and still the Three Lions have everything to play for.

For many, the inaugural competition's rules have been tricky to grasp since its debut round of fixtures in October. 

However, what we do know is qualification to the semi-finals or relegation is still a possibility for Gareth Southgate's side ahead of Sunday's finale against Croatia at Wembley. 

Still confused as to how either outcome can happen? Well - we've got you covered with our handy explainer below.  

Come on, England! 

Recap - what is the UEFA Nations League?

Gareth Southgate

Gareth Southgate

The format sees 55 European national teams divided into four pots - A, B, C and D with each pot running four leagues of three teams, which were decided by UEFA's national association coefficient rankings on 11 October 2017. Each country will play each other home and away. 

Teams from the A leagues - including England - compete for top spot and a place in the UEFA Nations League semi-final. Teams who finish bottom of their group will be relegated to League B for the 2020 edition while finishing 2nd keeps those teams in the same league. 

Countries who are not in League A are unable to qualify for the semi-final stage with League B and League C fighting sorely for promotion and relegation. As League D is the bottom tier, relegation is not possible. 

The current Group A4 table stands as followed: 

1. Spain - Played: 4. Points: 6. Goal difference: +5

2. England - Played: 3. Points: 4. Goal difference: 0 

3. Croatia. Played 3: Points: 4. Goal difference -5

How can England qualify for the UEFA Nations semi-final stage?

It's a case of winner takes all at Wembley on Sunday. 

Following Croatia's 3-2 win over Spain on Thursday evening, a victory for England will see them into the semi-final stage.

But if Croatia win, they will top the group and in the process, relegate England. 

Pretty simple on that front - however matters get slightly tricky should the tie end in a draw... 

How can a draw relegate England to League B?

With England holding both the better head-to-head record and goal difference, a draw against Croatia will keep the Three Lions in League A - right?

Well, not entirely... 

If it ends with a 0-0 scoreline, England will avoid relegation. 

But if the two sides play out a score draw, because England failed to score in a 0-0 stalemate in Croatia last month, Southgate's side will be relegated on the away goals rule. 

What happens next? Who could England face in the next round? 

No other country from group A1, A2 and A3 are yet to secure their place in the semi-final stage. 

If England top the group, they could face France, Netherlands, Belgium, Switzerland, Portugal or Italy.

The three definite teams will be confirmed once each country has contested their final group match. 

Just like the World Cup, a win or a defeat in the semi-final decides whether it is to be a place in the final or a third place playoff in June 2019. 

Iceland and Poland are already confirmed as relegated while Germany need to beat Netherlands to retain their League A status.