The Premier League is facing the threat of legal action from a club over amended rules around commercial deals.
On Friday, rules regarding associated party transactions (ATPs) were tightened, aimed at clubs signing sponsorship deals with companies linked to their owners.
ATPs can inflate revenue streams and allow more room for spending.
League officials have not named the club but informed all 20 of the threat at a shareholders’ meeting in London.
The legal threat surrounds whether the Premier League’s rules are compatible with competition law.
BBC Sport has been told the threat remains even though a vote on the proposed rule changes, following an earlier review, gained enough support to be passed after it had been rejected in November.
The changes will be introduced to the Premier League handbook in a matter of weeks but one contentious element around personal liability to directors has been removed.
It is understood the vote was not unanimous.
Sources have pointed to that disagreement, plus ongoing charges against Everton, Nottingham Forest and Manchester City and behind-the-scenes complaints about the new Premier League TV deal, as evidence of fractured relationships within the Premier League and discontent with chief executive Richard Masters.
“Following a full review of the existing associated party transactions rules and fair market value assessment protocols, clubs agreed to a series of amendments to further enhance the efficiency and accuracy of the system,” said a Premier League statement.
Meanwhile, the Premier League is still not in a position to put a funding package to the English Football League (EFL).
Funding of around £900m has been agreed but issues over where the money should come from and stipulations around cost controls in the Championship have stalled completion of the deal, much to the frustration of EFL clubs.
However, sources have said there is now momentum behind the discussions and pointed to a good-natured gathering of some Premier League and EFL clubs on Wednesday as evidence of the scope for agreement.
Clubs were also told there would be no pre-season Summer Series in 2024 because of a combination of time constraints, the European Championship and Copa America.