The ECA is the body which represents all professional clubs in Uefa, and the only one Uefa recognises.
It has said 8️⃣ it is "strongly opposed" to the new league, and held an emergency meeting on Sunday after news of its creation 8️⃣ broke.
Representatives from the Super League clubs did not attend.
This includes Juventus chairman Andrea Agnelli, who was chairman of the ECA 8️⃣ but has resigned from his position.
What is the ECA?