1991 - From traditional knockout stage to “semi-final group stage”
For many young fans, the Champions League represents the presence of many clubs from many countries, but the European Cup was originally only for the champions of each country and the defending champions. From its inception in 1955 until 1991, the format was a traditional knockout, with home/away ties over two legs, to determine the final two teams on neutral ground.
The 1991–92 season was the last time the tournament was called the European Cup, and saw the introduction of a group stage. The first and second knockout rounds saw the 32 teams reduced to eight, which were then split into two groups of four teams each. This was known as the “semi-final group stage”. Barcelona and Sampdoria finished top of their respective groups and faced off in the final at Wembley, where the Catalans won 2–0.
The tournament was renamed the Champions League the following season but kept the same format. Marseille and AC Milan finished top of their groups to compete in the final, which the French side won. In the 1993–94 season, the eight-team group stage was retained. However, the format was slightly changed, with the top two teams from each group advancing to a one-off semi-final.
That year, Barcelona topped Group A and played Group B runners-up Porto at home, while Milan topped Group B and played Monaco. Barca and Milan advanced to the final, where the Serie A giants beat the 1992 winners 4-0 in Athens.
1994: The first group stage takes shape
The next big change came the following season (1994–95) when the first knockout rounds were now qualifiers for a new 16-team group stage, consisting of four groups of four teams each. The top two teams from each group advanced to the knockout stages, which were quarter-finals and semi-finals over two legs. Defending champions Milan again reached the final, where they were beaten 1–0 by Ajax in Vienna. The following two seasons followed a similar format, with the defending champions, oddly enough, being beaten in both finals – Juventus beating Ajax on penalties in 1996, then the Italians being beaten by Dortmund in 1997.
1997: More groups, more teams
The tournament was expanded to 24 teams for the 1997–98 season, with runners-up from several of the top national leagues instead of just the champions. The 24 teams were divided into six groups of four. The top six teams advanced to the quarter-finals and the two best runners-up advanced to the quarter-finals, giving the teams competing for second place an extra incentive. Real Madrid won that year, beating Juventus in the final.
This format was retained in the 1998–99 season which Manchester United won in their famous treble season.
1999: Second group stage added
Another major change came in the 1999-2000 season, when the number of teams increased to 32 - including some third and fourth-placed teams from their domestic leagues - and the teams were divided into eight groups of four teams each. The 16 teams (group winners and runners-up) advanced to the second round, where the competition was played in a similar format, with the top two teams from each group advancing to the quarter-finals.
2003: Second group stage eliminated
The two group stages were maintained for three seasons until UEFA abolished the second group stage and replaced it with a knockout round of 16 from the 2003-2004 season. This format remained unchanged for 21 seasons, until this season, when UEFA abolished the group stage altogether and played a 36-team league format. Although each team only played 8 matches, the overall rankings were used to determine the 8 teams that would qualify directly for the round of 16, with the teams ranked 9th to 24th playing a play-off for the remaining 8 tickets. The remaining teams would be eliminated and would not be transferred to the Europa League.
