Every team in the league phase of the revamped Champions League was beaten at least once.
So there will be no unbeaten winner in the 2024/25 edition of the continental competition.
But in the history of the European Cup, 12 clubs have gone through to win the trophy without losing a single match. And some have done it more than once.
Here, a look at the European champions that went unbeaten through an entire campaign...
Inter (1963/64)
Inter won the European Cup for the first time in 1963/64, beating Real Madrid 3-1 in the final at Vienna's Praterstadion in late May.
The Nerazzurri went unbeaten in the continental competition, with two draws and seven wins en route to the title. The Milan club won the trophy again the following season.
Ajax (1971/72)
The great Ajax side of the early 1970s won the second of three consecutive European Cups in 1971/72, beating Inter 2-0 in the final in Rotterdam thanks to two goals from Johan Cruyff.
That result saw the Amsterdam club complete an unbeaten European campaign, taking the title after seven wins and two draws in their nine matches.
Nottingham Forest (1978/79)
Nottingham Forest finished as runners-up to Liverpool in the First Division in 1978/79, but Brian Clough's side knocked the Reds out of the European Cup in the first round.
Forest went all the way to the trophy, edging out Swedish side Malmö by a single goal in the final at Munich's Olympiastadion and finishing their continental campaign unbeaten, with six wins and three draws.
Liverpool (1980/81)
Alan Kennedy's 82nd-minute goal gave Liverpool a 1-0 win over Real Madrid in the 1981 European Cup final at the Parc des Princes in Paris.
The Reds won six and drew three of their nine fixtures to finish the campaign unbeaten, but beat Bayern Munich in the last four without a victory, advancing after a 0-0 draw at Anfield and a 1-1 tie in Germany.
Liverpool (1983/84)
Liverpool won the European Cup again in 1984, beating Roma on penalties at the Italian side's Stadio Olimpico home after a 1-1 draw.
The Reds also drew 0-0 away to Athletic Club in the second round, but beat the Basques 1-0 at Anfield and won their other six matches en route to the final.
AC Milan (1988/89)
AC Milan are seven-time European Cup winners and the Rossoneri took the title without losing a single match in the 1988/89 edition.
In the second round of the continental competition, Milan were a goal down away to Red Star Belgrade when the match was suspended due to thick fog. In a replay played the following night, Arrigo Sacchi's side won on penalties after a 1-1 draw and went on to thrash Real Madrid 6-1 on aggregate in the last four before a 4-0 victory over Steaua Bucharest in the final. In total, Milan won five and drew four of their nine games.
Red Star Belgrade (1990/91)
Denied by AC Milan and thick fog in 1989, Red Star Belgrade enjoyed better luck in the 1990/91 European Cup, going on to win the trophy with victory on penalties against Marseille in the final.
That followed a goalless 120 minutes in Bari. Previously, the Yugoslavian champions (a Serbian side these days) had knocked out Grasshoppers, Rangers, Dynamo Dresden and Bayern Munich, winning five and drawing three en route to the final.
Olympique Marseille (1992/93)
Two years after missing out to Red Star Belgrade in the 1989 European Cup final, Olympique Marseille won the trophy with a 1-0 win over AC Milan at Munich's Olympiastadion.
Marseille won three and drew three to finish a point above Rangers in the group stage, with Basile Boli's goal securing victory in the final. OM had previously won three and drawn one in the preliminary rounds. Inaugural winners of the Champions League after the competition was rebranded for the 1992/93 season, Marseille also became the first French team to get their hands on the European Cup.
AC Milan (1993/94)
AC Milan thrashed Barcelona 4-0 in Athens to claim the European Cup for the third time in the space of five years.
It was a first title in the Champions League era for Milan, beaten by Olympique Marseille in the final the previous season, and completed an unbeaten European campaign for the Rossoneri. Including the qualifying rounds, Fabio Capello's side won seven games and drew five overall.
Ajax (1994/95)
Ajax won the Eredivisie title without losing a single match in 1994/95 season and the Amsterdam outfit replicated that feat in the Champions League.
Louis van Gaal's side won seven and drew four en route to the title, thrashing Bayern Munich 5-2 in the teams' semi-final second leg and going on to beat AC Milan 1-0 in the final in Vienna.
Manchester United (1998/99)
Manchester United came from a goal down in the closing stages against Bayern Munich to win the Champions League – and complete a treble – in epic fashion at Camp Nou in May 1999.
After a win and a draw in the second qualifying round, United won five matches and drew six in the group phase and knockout stages to seal an unbeaten European campaign in an unfortgettable season.
Barcelona (2005/06)
Barcelona won the European Cup for the first time in 1991/92, which was the final season before the competition was rebranded as the Champions League.
Under Frank Rijkaard, Barça went on to win the Champions League in 2005/06 and the Blaugrana took the title without losing a game, with nine wins and four draws culminating in a 2-1 victory over Arsenal in the final in Paris.
Manchester United (2007/08)
Manchester United won the Champions League for a second time under Alex Ferguson in 2008 and once again, the Red Devils completed an unbeaten campaign.
United beat Chelsea on penalties in the final after a 1-1 draw in Moscow to claim the European Cup for a third time overall, winning nine games and drawing four en route to the trophy.
Bayern Munich (2019/20)
Due to the Covid-19 pandemic, the Champions League was played in one-off ties at neutral venues, and behind closed doors, from the quarter-finals onwards.
Bayern Munich went on to win the competition, thrashing Barcelona 8-2 in Lisbon in the last eight and going on to edge out Paris Saint-Germain by a single goal in the final. Impressively, Hansi Flick's side won all 11 of their matches in a historic campaign, which also featured Bundesliga and DFB-Pokal victories in a treble triumph for the Bavarian giants.
Manchester City (2022/23)
Manchester City completed a historic treble in 2022/23, culminating in a 1-0 win over Inter in the Champions League final in Istanbul.
Pep Guardiola's side won eight and drew five of their 13 fixtures in the continental competition, beating Real Madrid 5-1 over two legs in the last four and going on to win the trophy for the first time courtesy of Rodri's goal against Inter in the final.
Real Madrid (2023/24)
It may seem logical that Real Madrid are one of the teams to have won the European Cup without losing a match. After all, Los Blancos are 15-time champions.
But Madrid had to wait until 2023/24 to go unbeaten in the competition, with Carlo Ancelotti's side winning nine games and drawing four en route to the title. Two of those draws came against Manchester City in the last eight, with Los Blancos prevailing in a penalty shootout. Real beat Borussia Dortmund 2-0 in the final at Wembley.
