The Italian Football Federation (FIGC) has approved a rule that would ban clubs who sign up to breakaway competitions from competing in Serie A.
It follows the collapse of the proposed European Super League which involved Juventus, Inter Milan and AC Milan.
The tournament sparked furious backlash but Juve, plus Barcelona and Real Madrid, are yet to abandon the project.
Clubs playing in leagues not recognized by FIFA or UEFA will now not be able to play in domestic tournaments in Italy.
The FIGC added a new clause to its rules underlining that clubs registering for national leagues must agree they will not join private, unauthorized competitions.
Under the European Super League proposals announced on 18 April, clubs agreed to play in the new competition but wanted to continue to play in their domestic leagues.
