A fourth club has been named alongside Burnley, Leeds United and Leicester City as they look set to take legal action against Everton.
The football world was rocked on Friday, when it was announced that Everton will receive a ten-point deduction after being found guilty of breaching the Premier League's profitability and sustainability rules for the period ending 2021-22.
The club, who now sit in the relegation zone with four points, said they were "shocked and disappointed" by the ruling. They will appeal what is the heaviest points punishment in Premier League history.
As the news began to circulate worldwide, it emerged that Leeds and Burnley had already been in contact with the Premier League.
Both clubs were interested in whether Everton broke spending rules during the pandemic, and a joint letter was signed off by Leeds chief executive Angus Kinnear and Burnley chairman Alan Pace that prompted the investigation, according to The Athletic.
A report from the Daily Mail has also emerged that suggests Leeds, Burnley and Leicester City are intending to sue Everton for a total of £300 million.
Senior figures at all three clubs held talks on Friday afternoon to reaffirm their plans to sue following the verdict, and agreed to follow through on their previous threats to sue Everton, which they formulated over the summer after Leeds and Leicester suffered relegation from England's top flight.
Burnley are believed to have offered their support as they remain 'convinced' that Everton's spending breached financial rules when they were relegated the season before.
And now, it appears Championship outfit Southampton are also threatening legal action, according to The Guardian.
Southampton suffered relegation from the Premier League last season after finishing rock bottom with six wins from a possible 38. Sean Dyche's side, meanwhile, avoided the drop by just two points.
The report also claims that Leeds, Leicester and Burnley have already written to Everton’s prospective new owners, 777 Partners, warning they intend to sue for damages in the event of a guilty verdict.
As mentioned earlier, Everton say they are 'shocked and disappointed' by the ruling.
They believe the commission has "imposed a wholly disproportionate and unjust sporting sanction', and have confirmed their intention to appeal.
The statement adds: "Everton maintains that it has been open and transparent in the information it has provided to the Premier League and that it has always maintained the integrity of the process.
"The Club does not recognise the finding that it failed to act with the utmost good faith and it does not understand this to have been an allegation made by the Premier League during the course of proceedings.
"Both the harshness and severity of the sanction imposed by the Commission are neither a fair nor a reasonable reflection of the evidence submitted.
"The Club will also monitor with great interest the decisions made in any other cases concerning the Premier League's Profit and Sustainability Rules."