Italian football federation president Gabriele Gravina has warned Juventus will be kicked out of Serie A if they do not withdraw from the European Super League.
With AC Milan and Inter Milan both backing out of the breakaway competition, Juve are the only Italian club remaining.
La Liga duo Real Madrid and Barcelona are also still committed, and, along with Juventus, released a statement at the weekend vowing to "persevere" with the Super League despite strong rejection.
Revenge for West Ham and redemption for Mark Noble - The Warm-Up
"The rules are clear. If Juventus is still part of the Super League when it enters next season, it can’t participate in Serie A," Gravina told Naples radio station Kiss Kiss.
"I am sorry, I saw some worried fans this morning, but everybody must respect the rules.
"Nine clubs decided to withdraw from the competition, there are three still involved. However, I hope this dispute will end soon."
The statement from the three remaining Super League clubs condemned the "intolerable pressure" that they claim has been put on them by UEFA and other "football stakeholders" since the collapse of the competition.
Arsenal launch shock Camavinga bid - Euro Papers
"The founding clubs have suffered, and continue to suffer, unacceptable third-party pressures, threats, and offenses to abandon the project and therefore desist from their right and duty to provide solutions to the football ecosystem via concrete proposals and constructive dialogue," the statement said.
Real, Barca and Juve also expressed "regret" at seeing the other nine clubs previously involved - including the ‘Big Six’ in the Premier League - recommit to UEFA on Friday.
Juventus could be set to miss out the Champions League next season after slipping down to fifth in Serie A. They are one point behind fifth-placed Napoli with three games of the season left to play.
Juventus claim first Serie A win of season as De Ligt decides five-goal thriller
Atletico and Juve keen on Saka as Arsenal demand at least £43m – Paper Round