The fifth edition of the UEFA Nations League kicks off its league phase on Thursday, September 23, 2026, involving 54 European national teams. Reigning champions Portugal, who secured the title in 2025, will begin their defense of the trophy. However, their path to a record third title is expected to be challenging, facing strong contenders including World Cup winners Spain and former champions France and England.

The UEFA Nations League was established in 2018 with the primary goal of replacing meaningless friendly matches with competitive fixtures between nations of similar standing. The competition operates on a league structure featuring promotion and relegation, offering teams more meaningful international games.

This season's tournament sees 54 teams divided into four leagues: A, B, C, and D. League A, the top tier, comprises 16 teams split into four groups. Notably, Group A3 features a formidable lineup of Spain, Croatia, England, and Czechia, while Group A1 includes France, Italy, Belgium, and Turkiye. Portugal headlines Group A4 alongside Denmark, Norway, and Wales.

The league phase will conclude by mid-November, with the top two teams from each League A group advancing to the quarterfinals in March 2027. The finals, featuring four teams, are scheduled for June 2027, though the host nation has not yet been determined. Winners of groups in Leagues B, C, and D will be promoted to the league above, while the bottom-placed teams in Leagues A and B face relegation.

Beyond the elite League A, League B also features 16 teams, divided into four groups, with promotion and relegation playoffs between Leagues A and B scheduled for March 2027. League C consists of 16 teams in four groups, and League D is the smallest, with three teams in Group D1 and three in Group D2. The playoffs between League C and D will take place in late March 2028.

UEFA has set specific dates for the league phase matches, with Matchdays 1 and 2 taking place from September 24-29, 2026. Subsequent matchdays are scheduled for early October and mid-November. This condensed schedule aims to provide a consistent flow of competitive international football throughout the season.

Historically, Portugal has been the most successful nation in the UEFA Nations League, winning the title twice. The inaugural tournament in 2019 was won by Portugal, and they repeated their success in 2025. Other past winners include France, who claimed the trophy in 2021, and Spain, who were victorious in 2023.

The competition format ensures that all teams play each of their group opponents twice, once at home and once away. This structure guarantees a minimum of six matches for teams in Leagues A and B, and a minimum of four or six matches for teams in Leagues C and D, depending on group size. The promotion and relegation system adds significant stakes to every match, encouraging teams to field their strongest lineups.