Hearts and Partick Thistle are claiming £10m from the SPFL should the courts rule not to overturn their relegations.
The pair lodged a petition with the Court of Session on Wednesday, with Hearts claiming £8m and Thistle £2m.
In a joint statement, they say they "have no wish to disrupt" Scottish football, but "reserve the right" to try to delay the Premiership season.
The pair had their demotions confirmed on Monday when clubs failed to support league reconstruction.
It followed a vote to curtail the term, with Hearts bottom of the Premiership and Thistle last in the Championship.
The pair said the action does not aim to "unravel the fee payments" to clubs or challenge the declaration of champions.
Their statement says their objective is "to reduce the unfair resolution insofar as it changed the SPFL's rules on promotion and relegation", and if that fails then they will seek £10m between them in compensation as an alternative remedy.
"As matters stand, we have not asked the Court to grant an interim interdict which would prevent next [Premiership] season commencing on 1 August," the statement said. "However, we have to reserve our right to do so in the event that becomes necessary.
"We would emphasise instead that we have no wish to disrupt Scottish football but rather our aim is to have the proceedings litigated to a conclusion as quickly as possible."
The SPFL now has seven days to respond to the petition, and a spokesman for the league said its solicitors are "studying this carefully".
Thistle previously said they could not afford the six-figure legal costs but an offer to fund court action led to them joining Hearts in challenging the SPFL's resolution to end the season.
The SPFL's reconstruction proposal - which would have reversed the demotions of Thistle, Hearts and Stranraer - failed after only 16 of the 42 clubs backed it.
All four senior divisions were curtailed because of coronavirus.