Andrea Agnelli has reportedly resigned as president at Serie A giants Juventus.
Real Madrid president Florentino Perez was also coming under intense pressure to follow suit on Tuesday night with the Super League set for collapse.
Both Agnelli and Perez had been leading figures in the formation of the Super League which - beset by a series of withdrawals - appears dead on arrival.
Manchester United vice-chairman Ed Woodward was the first to fall on his sword on Tuesday night as a result of the breakaway league's apparent failure to get off the ground.
Agnelli left his position as European Club Association (ECA) chairman at the weekend, after it was revealed he was vice-chairman of the Super League.
UEFA president Aleksander Ceferin was scathing in his assessment of the Super League ringleaders on Monday, saying, "If I start with Ed Woodward, because it will be shorter, I didn't have much contact with him but he called me last Thursday in the evening.
"He said he is very satisfied with the reforms, that he fully supports the reforms and that the only thing he would like to speak about is Financial Fair Play. Obviously, he had already signed something else.
"I don't want to speak much about Andrea Agnelli. He is probably one of the biggest disappointments or the biggest of all. I don't want to be too personal but the fact is that I have never seen a person that would lie so many times and persistently than he did. It was unbelievable.
"I spoke with him on Saturday afternoon and he said that these are only rumours, don't worry, nothing is going on, then he said I will call you in one hour and turned off his phone. The next day, we get the announcement.
"As I said, I have seen many things in my life but never this. Obviously, greed is so strong that all the human values evaporate. Everything is gone with some people.
"We are different and we will stay different. You know, it is always good to learn in life who is who.
"All the world knows now that they unanimously supported our reforms on Friday, when they obviously had signed the agreement [with the Super League].
"All that are sitting there: Woodward, Agnelli, [Ivan] Gazidis and Pedro Lopes from Real Madrid. I don't have to explain more what I think about them."
Perez was the first Super League boss to go public with their desire to force through the plan.
"Football is beginning to lose interest," the Real chief said on Monday night, "audiences are going down and television rights too, something had to be done, and the pandemic accelerated this process.
"Without change, we are ruined. 16-24 year old fans aren’t interested in football. 40% of young people aren’t interested in football, because there are too many games of low quality. It’s in all the statistics and the studies.
"Teenagers are more interested in playing video games than in football these days, and we have to do something to bring them back. We had to adapt. The same thing happened in the 50’s, UEFA and FIFA were opposed to Bernabéu and the European Cup.”