Germany and Ukraine are level on six points and both still in the title mix.
Germany are better placed though as they face Spain in the final day so have their destiny in their own hands.
Ukraine boss Andriy Shevchenko said: "As we are playing against a such strong team, especially away from home, we definitely will change our system.
"Yet we'll never abandon the foundations that I'm engraining into the players."
EPACopyright: EPA
Get Involved
#bbcfootball or text 81111 (UK only)
Sulaimon: Tonight is the night Sergio Ramos becomes the most capped international player. Despite the dark side of his game, he is an absolutely fantastic professional and he has trophies and goals to show for it. Vamos Ramos.
Lindelof & Kovacic start
Sweden v Croatia (19:45 GMT)
Manchester United defender Victor Lindelof starts for Sweden but Newcastle defender Emil Krafth has to settle for a place on the bench.
In the other game in Group A3, Croatia trail Portugal and France by seven points, while Sweden have lost all four of their matches so far.
It means Sweden must beat Croatia to have any chance of avoiding relegation to League B.
Croatia can't qualify for the finals but victory tonight will ensure their safety.
They come into this match off the back of a 3-3 friendly draw with Turkey on Wednesday - captain Domagoj Vida played the first half before finding out he had tested positive for Covid-19.
Sweden lost 2-0 to Denmark in their friendly on the same night - their third successive defeat.
Getty ImagesCopyright: Getty Images
Ramos breaks European record
Switzerland v Spain (19:45 GMT)
Sergio Ramos becomes the most capped European man ever with his 177th cap, taking him above Gianluigi Buffon’s previous record.
Unai Simon is preferred in goal to David de Gea and Kepa, while Manchester City's Ferran Torres is selected up front instead of Alvaro Morata.
Spain top A4 by one point from Germany, with Tuesday's meeting with the Germans likely to be winner takes all.
Switzerland - who have not won in almost a year (six games) - will be relegated if they lose in Basel today. They are unbeaten in 17 competitive home games though.
Switzerland coach Vladimir Petkovic said: "We need to stay calm and make fewer mistakes.
"There is too much talk about defensive mistakes, we also need to identify the mistakes we make in midfield, and the chances that we are missing."
ReutersCopyright: Reuters
Ronaldo & Griezmann start
Portugal v France (19:45 GMT)
Cristiano Ronaldo returns to the starting XI for Portugal after coming off the bench to score in the win over Andorra.
Manchester City duo Bernardo Silva and Joao Cancelo, as well as Manchester United's Bruno Fernandes are also back in the side.
Liverpool forward Diogo Jota is on the bench, alongside Wolves' trio Joao Moutinho, Pedro Neto and Ruben Neves.
Portugal XI: Rui Patricio, Dias, Guerreiro, Fonte, Ronaldo, Silva, Fernandes, Danilo, Carvalho, Cancelo, Felix
OptaCopyright: Opta
It's a strong team for world champions France too.
Barcelona's Antoine Griezmann, Chelsea's N'Golo Kante and Manchester United's Anthony Martial all return to the side.
Manchester United midfielder Paul Pogba keeps his place.
France suffered a shock 2-0 defeat to Finland in their friendly on Wednesday, ending a run of 12 matches unbeaten.
The world champions rotated heavily - Anthony Martial, Antoine Griezmann and N'Golo Kante were all on the bench - but Manchester United's Paul Pogba failed to impress.
Portugal, meanwhile, thrashed Andorra 7-0 in their friendly as Cristiano Ronaldo scored his 102nd goal and is now seven behind the all-time record of Iran's Ali Daei.
Victory for either side tonight will see them book their place in the Nations League finals.
They both sit level on points in Group A3 with 10 - Portugal ahead on goal difference.
Getty ImagesCopyright: Getty Images
Post update
Group A3:
Portugal v France
Sweden v Croatia
Group A4:
Germany v Ukraine
Switzerland v Spain
*All 19:45 GMT kick-offs
Four football giants in action
Portugal, France, Spain and Germany all in competitive action tonight? Uefa, you're really spoiling us.
Welcome to live text commentary of tonight's four Nations League games. Here's what's coming up...
Live Reporting
Emlyn Begley and Emma Sanders
All times stated are UK
'Never abandon foundations'
Germany v Ukraine (19:45 GMT)
Germany and Ukraine are level on six points and both still in the title mix.
Germany are better placed though as they face Spain in the final day so have their destiny in their own hands.
Ukraine boss Andriy Shevchenko said: "As we are playing against a such strong team, especially away from home, we definitely will change our system.
"Yet we'll never abandon the foundations that I'm engraining into the players."
Get Involved
#bbcfootball or text 81111 (UK only)
Sulaimon: Tonight is the night Sergio Ramos becomes the most capped international player. Despite the dark side of his game, he is an absolutely fantastic professional and he has trophies and goals to show for it. Vamos Ramos.
Lindelof & Kovacic start
Sweden v Croatia (19:45 GMT)
Manchester United defender Victor Lindelof starts for Sweden but Newcastle defender Emil Krafth has to settle for a place on the bench.
Sweden XI: Olsen, Lustig, Lindelof, Danielson, Bengtsson, Larsson, Ekdal, Berg, Forsberg, Kulusevski, Olsson
The usual suspects start for Croatia but they are without captain Domagoj Vida following that positive Covid-19 test.
Inter Milan midfielder Ivan Perisic and Real Madrid's Luka Modric are in the side, alongside Chelsea's Mateo Kovacic.
Croatia XI: Livakovic, Uremovic, Barisic, Perisic, Caleta-Car, Pongracic, Brekalo, Kovacic, Modric, Vlasic, Budimir
Must-win for Sweden
Sweden v Croatia (19:45 GMT)
In the other game in Group A3, Croatia trail Portugal and France by seven points, while Sweden have lost all four of their matches so far.
It means Sweden must beat Croatia to have any chance of avoiding relegation to League B.
Croatia can't qualify for the finals but victory tonight will ensure their safety.
They come into this match off the back of a 3-3 friendly draw with Turkey on Wednesday - captain Domagoj Vida played the first half before finding out he had tested positive for Covid-19.
Sweden lost 2-0 to Denmark in their friendly on the same night - their third successive defeat.
Ramos breaks European record
Switzerland v Spain (19:45 GMT)
Sergio Ramos becomes the most capped European man ever with his 177th cap, taking him above Gianluigi Buffon’s previous record.
Unai Simon is preferred in goal to David de Gea and Kepa, while Manchester City's Ferran Torres is selected up front instead of Alvaro Morata.
Spain XI: Simon, Reguilon, Ramos, Roberto, Torres, Merino, Ruiz, Busquets, Oyarzabal, Torres, Olmo.
Switzerland make seven changes from the side who lost 2-1 in a friendly to Belgium. Premier League pair Granit Xhaka and Xherdan Shaqiri start.
Switzerland XI: Sommer, Fernandes, Elvedi, Akanji, Rodriguez, Shaqiri, Zuber, Freuler, Xhaka, Seferovic, Embolo.
Post update
Switzerland v Spain (19:45 GMT)
Spain top A4 by one point from Germany, with Tuesday's meeting with the Germans likely to be winner takes all.
Switzerland - who have not won in almost a year (six games) - will be relegated if they lose in Basel today. They are unbeaten in 17 competitive home games though.
Switzerland coach Vladimir Petkovic said: "We need to stay calm and make fewer mistakes.
"There is too much talk about defensive mistakes, we also need to identify the mistakes we make in midfield, and the chances that we are missing."
Ronaldo & Griezmann start
Portugal v France (19:45 GMT)
Cristiano Ronaldo returns to the starting XI for Portugal after coming off the bench to score in the win over Andorra.
Manchester City duo Bernardo Silva and Joao Cancelo, as well as Manchester United's Bruno Fernandes are also back in the side.
Liverpool forward Diogo Jota is on the bench, alongside Wolves' trio Joao Moutinho, Pedro Neto and Ruben Neves.
Portugal XI: Rui Patricio, Dias, Guerreiro, Fonte, Ronaldo, Silva, Fernandes, Danilo, Carvalho, Cancelo, Felix
It's a strong team for world champions France too.
Barcelona's Antoine Griezmann, Chelsea's N'Golo Kante and Manchester United's Anthony Martial all return to the side.
Manchester United midfielder Paul Pogba keeps his place.
France XI: Lloris, Pavard, Kimpembe, Varane, Pogba, Griezmann, Martial, Coman, Kante, Rabiot, Hernandez
Winner takes all in Lisbon
Portugal v France (19:45 GMT)
France suffered a shock 2-0 defeat to Finland in their friendly on Wednesday, ending a run of 12 matches unbeaten.
The world champions rotated heavily - Anthony Martial, Antoine Griezmann and N'Golo Kante were all on the bench - but Manchester United's Paul Pogba failed to impress.
Portugal, meanwhile, thrashed Andorra 7-0 in their friendly as Cristiano Ronaldo scored his 102nd goal and is now seven behind the all-time record of Iran's Ali Daei.
Victory for either side tonight will see them book their place in the Nations League finals.
They both sit level on points in Group A3 with 10 - Portugal ahead on goal difference.
Post update
Group A3:
Portugal v France
Sweden v Croatia
Group A4:
Germany v Ukraine
Switzerland v Spain
*All 19:45 GMT kick-offs
Four football giants in action
Portugal, France, Spain and Germany all in competitive action tonight? Uefa, you're really spoiling us.
Welcome to live text commentary of tonight's four Nations League games. Here's what's coming up...