The Champions League is the most watched club football competition in the world. It also changed its format significantly in 2024 — so this covers both the classic group stage structure and the new league phase, since community organizers draw on both.
The Classic Format: Group Stage (Pre-2024)
For decades, the Champions League used a group stage followed by knockout rounds. 32 teams were drawn into 8 groups of 4. Every team played every other team in their group twice — once at home, once away. Points: 3 for a win, 1 for a draw, 0 for a loss.
The top 2 teams from each group advanced to the Round of 16. Third place dropped into the Europa League. Fourth went home.
Groups were drawn using a pot system based on UEFA coefficient rankings. Clubs from the same country couldn't be drawn into the same group — preventing domestic rivals from meeting until the knockout stages.
The New Format: League Phase (2024–25 Onward)
Starting in 2024–25, UEFA expanded the field to 36 teams and replaced the group stage with a single league table. No groups. Each team plays 8 opponents (4 at home, 4 away) selected through a seeded draw.
At the end of the league phase:
- Top 8 advance directly to the Round of 16.
- 9th to 24th enter a knockout playoff round for the remaining 8 spots.
- 25th and below are eliminated.
UEFA's argument is that the new format keeps more matches meaningful for longer. In the old group stage, a team that won its first three games could rest players in the last three. The league phase keeps 36 teams jostling for position until the final matchday.
The Knockout Rounds
Both formats use the same knockout structure from the Round of 16 onward. Every tie is played over two legs: a home game and an away game. Aggregate score over both legs determines who advances.
If it's level on aggregate after 90 minutes of the second leg, 30 minutes of extra time are played. Still level — penalties. Away goals no longer count double; UEFA dropped that rule in 2021. It's aggregate only now.
The rounds:
- Knockout playoffs (new format) / Round of 16 entry (old format)
- Round of 16
- Quarter-finals
- Semi-finals
- Final — single game, neutral venue
Why Two Legs?
Revenue is the honest answer — each match generates significant broadcast income, so running one knockout game instead of two halves that. But there's a genuine sporting argument too: over two legs, a one-goal error is recoverable. The tactical dynamics of a team protecting a first-leg lead, or needing to score twice while not conceding, create situations that don't exist in one-off games.
The final is a single game at a neutral venue. It needs to be an event, not another leg in a series.
Applying This to Community Tournaments
The group stage + knockout structure is one of the most effective formats in sport. It guarantees every team multiple matches before elimination — important when teams have traveled to compete. A simple version:
- 8 teams: 2 groups of 4 → top 2 from each into semi-finals
- 12 teams: 3 groups of 4 → top 2 advance plus the best third-placed team
- 16 teams: 4 groups of 4 → top 2 from each into quarter-finals