The Premier League has "unanimously and vigorously rejected" proposals for a Super League and is planning to take action against the six sides from the English top-flight that have signed up for the new European competition.
Manchester United, Chelsea, Arsenal, Tottenham, Liverpool and Manchester City announced on Sunday that they intend to form part of a new breakaway competition involving members of the continental elite.
They have been joined in that venture by Barcelona, Real Madrid, Atletico Madrid, Juventus, Inter and AC Milan - with the intention being to welcome others on board - but opposition to the project is threatening to undermine their efforts.
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What has been said?
The Premier League has responded to the plans by announcing in a statement: "The Premier League, alongside The FA, met with clubs today to discuss the immediate implications of the Super League proposal.
"The 14 clubs at the meeting unanimously and vigorously rejected the plans for the competition. The Premier League is considering all actions available to prevent it from progressing, as well as holding those Shareholders involved to account under its rules.
"The League will continue to work with key stakeholders including fan groups, Government, UEFA, The FA, EFL, PFA and LMA to protect the best interests of the game and call on those clubs involved in the proposed competition to cease their involvement immediately.
"The Premier League would like to thank fans and all stakeholders for the support they have shown this week on this significant issue. The reaction proves just how much our open pyramid and football community means to people."
Who else has spoken out against the Super League?
Managers, players from past and present, supporters and sporting organisations from around the world have condemned the actions of a dozen clubs at the heart of Super League plans.
Many have vowed that sanctions will be imposed on any clubs that break away from the establishment and head out on their own.
FIFA president Gianni Infantino has said: "There is a lot to throw away for maybe a short-term financial gain of some. People need to think very carefully. They need to reflect and they need to assume responsibility.
"If some elect to go their own way, then they must live with the consequences of their choice. They are responsible for their choice. Concretely, this means either you are in or you are out. You cannot be half in or half out."
UEFA supremo Alexander Ceferin has stated: "Those clubs who think they are big and untouchable today should remember where they came from. And they should realise that if they are European giants today, it is partly thanks to UEFA."
Ceferin has previously stated that any team involved in the Super League will be prevented from figuring in the Champions League or Europa League, while international players run the risk of being banned from representing their countries.
It has also been suggested that the clubs involved could be kicked out of their domestic divisions, with the Premier League meeting with the 14 clubs that are not part of the Super League project in a bid to piece together a plan of action.