Six English clubs have agreed to join the breakaway Super League.
Arsenal, Chelsea, Liverpool, Manchester City, Manchester United and Tottenham have joined three clubs from Italy and three from Spain to form a rival competition to the Champions League.
Here the PA news agency looks at the history and credentials of the 12 clubs involved.
AC Milan
Founded: 1899.
Owners: Elliott Management Corporation (USA).
Euro best: Seven-time European champions. Three titles between 1989 and 1994 under Arrigo Sacchi and Fabio Capello, but none since 2007.
What are you doing here? Lived on past glories for some time. Spent only two seasons outside Serie A since formation but overtaken by Italian rivals in recent years. Absent from the Champions League since 2013-14 and in the Europa League for the last three seasons. Improved this year and second in Serie A.
Arsenal
Founded: 1886.
Owners: Kroenke Sports & Entertainment (USA).
Euro best: One Champions League final in 2006 – lost to Barcelona. Picked up one European Cup Winners' Cup (1994) and Inter-Cities Fairs Cup (1970).
What are you doing here? Qualified for every European season since 1996-97, including all Champions League campaigns from 2001-17, but hardly set the world alight. Spent last four seasons in the Europa League and are ninth in the Premier League after another underwhelming campaign.
Atletico Madrid
Founded: 1903.
Owners: Miguel Angel Gil Marin, Idan Ofer, Enrique Cerezo.
Euro best: Won the Cup Winners' Cup in 1962 and three Europa League titles since 2010. Have reached three European Cup/Champions League finals but never lifted the main prize.
What are you doing here? Muscled in on the big boys with eight successive seasons of Champions League football under Diego Simeone. But spent only one season in Europe's main competition between 1978 and 2008. Top of LaLiga at present.
Barcelona
Founded: 1899.
Owners: Barcelona is organised as a registered association. Owned by fans of the club and has 170,000 registered members.
Euro best: Had to wait until 1992 to be crowned European champions, but have since picked up four more titles in 2006, 2009, 2011 and 2015.
What are you doing here? Perennial trophy winners and one of the biggest clubs in the world, with their Nou Camp home holding almost 100,000 people. Spent every season since 1955 in one or more European competition and sit third in LaLiga.
Chelsea
Founded: 1905.
Owners: Roman Abramovich (Russia).
Euro best: Won the Champions League in 2012 and claimed two Europa League titles.
What are you doing here? Spent more seasons in the second tier of English football than the top flight between 1975 and 1989. But fortunes improved in the 1990s and Abramovich's wealth them turned them into a major Premier League player. Fifth in the Premier League and have a Champions League semi-final to look forward to.
Inter Milan
Founded: 1908.
Owners: Suning Holdings Group (China)
Euro best: Back-to-back European Cups in 1964 and 1965 and a Champions League triumph in 2010 with Jose Mourinho at the helm.
What are you doing here? Italy's top team this season under Antonio Conte and Serie A champions elect with a nine-point lead over city rivals Milan. But little Champions League pedigree of late with only one quarter-final appearance since winning the trophy 11 years ago.
Juventus
Founded: 1897.
Owners: The Agnelli family (Italy).
Euro best: Crowned kings of Europe twice – in 1985 and 1996. Last European silverware was the Intertoto Cup in 1999.
What are you doing here? Regular champions of Italy and claimed a ninth successive title last season. But they have slipped this year and sit 13 points adrift of Serie A leaders Inter in fourth, despite having Cristiano Ronaldo in their side.
Liverpool
Founded: 1892.
Owners: Fenway Sports Group (USA).
Euro best: England's most successful club in Europe with six European Cup/Champions League titles – 1977, 1978, 1981, 1984, 2005 and 2019. Backed that up with three UEFA Cup victories.
What are you doing here? Did not play in Europe's top competition after being finalists in 1985 until 2001. Back among the main contenders under Jurgen Klopp in recent years and crowned champions of England for a 19th time last season. Having to fight for Champions League qualification this term.
What they said: Liverpool manager Jurgen Klopp, in 2019: "For me, the Champions League is the Super League, in which you do not always end up playing against the same teams."
Manchester City
Founded: 1880.
Owners: The City Football Group.
Euro best: Never made a Champions League final, although Pep Guardiola's side are in the last four this season. One Cup Winners' Cup success in 1970.
What are you doing here? Six English titles. Four of them have come since 2012 and are poised to win a fifth. Played in third tier of English football in 1998-99 and for so long were in the shadows of local rivals Manchester United. But 2008 takeover by Sheikh Mansour Bin Zayed Al Nahyan transformed their fortunes.
Manchester United
Founded: 1878.
Owners: The Glazer family (USA).
Euro best: Three European Cups/Champions League triumphs in 1968, 1999 and 2008 and twice beaten finalists. Also won the Cup Winners' Cup and the Europa League.
What are you doing here? Traditional heavyweights of English football, despite spending the 1974-75 season in the second tier. Won a record 20 English top-flight titles, 13 of them coming during Sir Alex Ferguson's reign between 1986 and 2013. Currently second in the Premier League.
What they said: Executive vice-chairman Ed Woodward, in 2020: "I saw the reports on that (Super League) and candidly don't know where that story came from, but there isn't really anything for us to say."
Real Madrid
Founded: 1902.
Owners: Real Madrid, like Barcelona, are a registered association and owned by supporters. The 'socios' are in charge of electing the president and the club's board.
Euro best: Dominated the early years of the European Cup by winning five in a row between 1956 and 1960. Recorded four Champion Leagues successes between 2014 and 2018 and have won a record 13 European titles. Semi-finalists again this season and second in LaLiga.
What are you doing here? No self-respecting European breakaway would take place without Real. The self-styled kings of European football have six more titles in the main competition than their closest challengers Milan.
Tottenham Hotspur
Formed: 1882.
Owners: ENIC International Limited.
Euro best: Champions League finalists in 2019. Winners of the Cup Winners' Cup (1963) and UEFA Cup (1972, 1984).
What are you doing here? Just two English titles, the last one of which came in 1961. No trophy since the League Cup in 2008, although back in the final of that competition on Sunday. Have a grand total of six European Cup/Champions League campaigns and are seventh in the Premier League this season.
