The Champions League changed fundamentally in 2024-25, replacing the 32-team group stage that had run since 2003 with a 36-team league phase based on the Swiss model. Instead of eight groups of four, all 36 clubs now sit in a single league table, and each team plays eight matches against eight different opponents, four at home and four away. The matchups are decided by a seeded draw before the season starts.

The Swiss model means no team plays every other team, which is the point. Clubs are drawn against two opponents from each of four seeding pots, so every team faces a mix of strong and weaker opposition. This replaced the old system where a team played the same three opponents home and away, and it was designed to create more high-profile matches early in the competition. The seeded draw uses four pots based on club coefficients, so each team faces two clubs from each pot, which is designed to balance the difficulty of every schedule as fairly as possible. This also means traditional group-stage rematches are rarer, since teams no longer play the same opponent twice in the opening phase.

At the end of the league phase, the top eight teams qualify directly for the round of 16. Teams finishing ninth to 24th enter a two-legged knockout play-off round, with the higher-ranked teams facing the lower-ranked ones. The winners complete the last 16. Teams finishing 25th to 36th are eliminated outright, and, unlike the old format, they do not drop into the Europa League.

From the round of 16 onwards, the competition follows its traditional knockout format: two-legged ties through to the semi-finals, with extra time and penalties if the aggregate score is level. The away goals rule no longer applies, a change that was already in place before the new format arrived. The final remains a single match at a neutral venue. The play-off round adds two extra matches for the teams finishing ninth to 24th, which increases fixture load but also keeps more clubs alive deeper into the season than the old format did. For clubs that finish in the top eight, the reward is rest: they skip the play-offs entirely and go straight to the round of 16.

For the 2025-26 season, UEFA added a small but significant tweak: teams finishing in the top four of the league phase are now guaranteed to host the second leg of their round of 16 and quarter-final ties. This rewards a strong league-phase finish more directly than before, giving clubs a real incentive to chase every point rather than settling for a top-eight finish.

The new format also means more football. Each club plays eight league-phase matches instead of six group games, and a team reaching the final can play up to seventeen matches in a season. Critics worried about fixture congestion and player workload, while supporters of the change pointed to more meaningful games and fewer dead rubbers, since every position in the table matters for qualification or seeding. Fixture congestion remains the main criticism, with players and managers arguing that eight league-phase matches plus a possible play-off round leaves little room for recovery in an already packed calendar. UEFA has defended the format by pointing to higher attendances and television audiences for the extra matchdays, which suggests supporters enjoy the additional big games.

The early evidence suggests more goals and more attacking football, with the extra matches and the single-table format encouraging teams to chase goal difference as a tiebreaker. Whether that trend lasts will depend on how coaches adapt, but the first two seasons under the new system have already produced several high-scoring matchdays.

For fans, the simplest way to follow the league phase is to watch the table, not a group. Every result affects every club's position, and the battle for eighth place, or 24th place, can be as tense as any old group decider. The format is more complex, but once you follow the table, it makes sense.