The case against the SPFL that has embroiled Dundee United begins at the Court of Session today.
The action taken by Hearts and Partick Thistle threatens to halt the promotions of respective divisional champions United, Raith Rovers and Cove Rangers.
It is expected to start at 11am, with proceedings taking place via teleconference.
After league reconstruction talks collapsed, Jambos owner Ann Budge launched the legal bid with Thistle which contains a claim of up to £10 million in compensation.
The case has been brought because of a resolution that was passed by the majority of the 42 SPFL member clubs in April.
It decided final placings in the Championship and the other two divisions on a points-per-game basis.
The vote also gave the SPFL board the power to take the same action in the Premiership, which they subsequently did.
Thereafter, a proposal to reconstruct the leagues to a 14-10-10-10 structure was rejected by the member clubs.
In the court papers, which have seen by Courier Sport, lawyers acting for Hearts and Thistle stress the need for a quick resolution because of the threat of fixtures being produced for the new campaign – the Premiership is due to start on August 1 – without their names included in the top flight and Championship respectively.
They are asking for an interim interdict to prevent such a restart, threatening the Premiership’s lucrative new broadcast deal with Sky Sports.
Dundee’s controversial no-then-yes vote to end the season below the Premiership also forms a crucial part of the case.
The Jambos and the Jags want the Dark Blues’ initial stance to stand and therefore nullify the original resolution.
Last month United legend Maurice Malpas criticised the Hearts and Thistle for dragging the Terrors into their legal dispute.
He said: “It shows a lack of respect for Scottish football and the rest of the teams in the SPFL.
“I know it isn’t fair on Hearts and Partick Thistle but that is what the other clubs voted for.
“You can understand Hearts and Thistle having a gripe because there were still a few games to play and they still had a chance of staying up.
“The issue is that they have gone and spat the dummy out at the wrong people.
“It is wrong they are challenging United, Raith and Cove. These teams haven’t done anything wrong.
“Why should Hearts and Thistle have a bite at them?”