Champions League is a club association football competition operated by Europe’s top-tier league, the Union of European Football Associations (UEFA). It features the reigning champions of each of UEFA’s 53 national leagues and clubs that earn invitations through other qualification streams. The competition is one of the most watched and highest regarded in the world, behind only the FIFA World Cup and the UEFA European Championship.
The competition began in 1960 as a single-elimination tournament for teams only from one nation, but has since been expanded to include the best clubs from the five continental member confederations of the Federation Internationale de Football Association (FIFA) and other high-ranking clubs. It is the top-tier competition of the European football season and is contested by 32 clubs over two legs, with the final being played in a neutral venue selected by UEFA.
In 2024/25, the competition format was substantially revised, dropping the group stage and replacing it with an expanded “league phase” in which all thirty-six qualified teams are ranked as a single group using a system based on four seeding pots to determine matchups. During the league phase, each team plays eight different opponents, with half of those games at home and the other at away.
The top-eight ranked clubs advance to the knockout play-off round, where they face the teams that finished nineth through twenty-fourth in the league table, with each of those matches also being two legged. Ahead of the start of the new format, UEFA explained that this arrangement is designed to increase both sporting and logistical incentives for teams in the league phase, and that it will provide the opportunity for a greater variety of matches in the bracket.