Champions League formats: from 16 champions to 36 clubs
The competition changed name, shape and size. Every change brought more money and fewer upsets.
The 1955 European Cup had 16 teams, all domestic champions. The 2024 Champions League has 36 clubs, mostly from five leagues.
Every format change was justified on sporting grounds; the outcome was always the same.
1955-1991: champions only
Straight knockout, no group stage, and plenty of shocks.
1992: a new name and group stage
More matches, more broadcast revenue, and from 1997 more than one entrant per country.
2003-2023: two decades of 32
Clubs from the top five leagues won 19 of 21 titles.
2024: 36 teams and a league phase
Eight matches against eight different opponents, with a play-off round.
What each change removed
Probability of an upset, and the sense of an exclusive tournament.
Conclusion
Upsets now need far more luck than they once did.