Cardiff City are set for a hearing in the French Courts on Monday as they sue FC Nantes for €120.2m (£105m).
Cardiff filed a complaint in Nantes Commercial Court against FC Nantes earlier this year with an initial hearing adjourned until December 8.
They are claiming losses of more than £100m following a dispute over Argentine striker Emiliano Sala's death.
The 28-year-old and a pilot, David Ibbotson, were both killed in a plane crash in the English Channel in January 2019. Ibbotson was flying Sala from Nantes to join Cardiff City, which was then a Premier League club, after the two clubs had agreed a transfer fee for the player.
Cardiff were relegated from the Premier League that season and have subsequently been relegated to League One. As part of what is expected to be a complicated hearing, which will be heard by a solitary Judge, Cardiff's legal team hope to argue that the loss of Sala contributed to their relegation on top of paying out a transfer fee for a player they could tragically never select.
The hearing is taking place in the French court system because the Swiss Federal Tribunal decided that the Court of Arbitration for Sport (CAS) did not have the jurisdiction to deal with Cardiff's claim.
The club said in April that an estimated figure of €120.2m (£105m) was being sought after "an in-depth analysis" by a legal expert.
Cardiff's lawyers will also attempt to argue in Court that FC Nantes had 'unequivocal' contact with former football agent Willie McKay, who was barred from operating as an agent at the time.
In February 2024 Cardiff City agreed an out-of-court settlement with Mr McKay, the terms of that settlement are understood to be confidential, but were reported to relate to the release of documents and messages about Sala's transfer.
In 2022 an Inquest jury found Sala died from head and chest injuries, but had become overcome by carbon monoxide from the aircraft's exhaust system that was flying him from Nantes to Cardiff and that he was most likely to have been unconscious when the plane crashed.
In late 2021 the person who organised the flight for Mr Sala - David Henderson - was jailed for 18 months. He was found guilty of recklessly endangering the safety of an aircraft and he also admitted to a charge of trying to arrange a flight for a passenger without permission or authorisation.
Ahead of the court hearing in Nantes, Cardiff have said: "This tragedy, which began nearly seven years ago, cost Emiliano Sala his life. It is a tragedy that could and should have been avoided… On the eve of the hearing, however, there is hope. The hearing marks another step towards uncovering the truth and establishing more accountability in football.
"This case isn't about harming football: it's about protecting its integrity. This is about ensuring higher standards across our sport, especially surrounding transfers. Because Emiliano Sala deserved better. Because football deserves better."
Cardiff say they have full confidence in the French justice system with the one-day hearing scheduled to begin at 4pm French time (3pm GMT) with the an expected judgement to be delivered by spring 2026.