The Champions League stopped being a tournament of small groups and became something closer to a single giant league table. If you last followed it when four-team groups decided everything, the modern format will look unfamiliar for about ten minutes and then make complete sense.
One table, thirty-six teams
Every qualified club enters a single league phase. All thirty-six sit in the same table. They do not, however, all play each other, which would mean 35 matches per club and a season that never ended. Instead each club plays eight matches against eight different opponents, four at home and four away.
Opponents are drawn from seeded pots based on club coefficient, so each team faces two opponents from each pot. That is the mechanism that guarantees a spread of difficulty: nobody gets eight easy fixtures and nobody gets eight brutal ones. Clubs from the same national association are kept apart in the league phase.
What the table decides
Finish in the top eight and you go straight into the round of 16. That is the prize worth chasing, because it means skipping an extra two-legged tie in the middle of winter.
Finish between ninth and twenty-fourth and you enter a knockout playoff round, seeded so the higher-placed teams get the second leg at home. Winners of those ties join the top eight in the round of 16.
Finish twenty-fifth or lower and your European season is over. There is no parachute into the Europa League any more, so the drop that used to soften group-stage elimination has been removed.
Why the format changed the competition
Two things happened. First, a single table makes every match matter to everyone. A late goal in a game you are not watching can move you three places, which is why the final round of league-phase fixtures is played simultaneously.
Second, it rewards consistency over survival. Under the old groups, a club could lose four matches and still advance by beating the weakest team twice. Now eight results are measured against thirty-five rivals, and goal difference across the whole league phase becomes a genuine tiebreaker rather than a formality.
The knockout half
From the round of 16 onward the competition returns to what it always was: two legs, home and away, aggregate score, extra time and penalties if level after the second leg. The away-goals rule is gone, so 1-1 away and 0-0 at home goes to extra time rather than through on away goals.
The bracket is determined by league-phase seeding, which means a strong league phase does more than get you through. It shapes who you meet in March.
The short version
Thirty-six clubs, one table, eight matches each. Top eight advance directly. Ninth to twenty-fourth play a knockout playoff. Twenty-fifth and below go home. Then a conventional two-legged bracket to a one-off final at a neutral stadium.