Manchester City chairman Khaldoon Al Mubarak admitted he absolutely regrets the club's involvement in the proposed European Super League, though he vowed to continue to "disrupt" the world's elite.
Nine of the 12 rebel clubs who signed up to the breakaway competition announced in April, have withdrawn from the proposals amid a huge external backlash.
Juventus, Real Madrid and Barcelona alone continue to pursue the idea, insisting football is facing an "inevitable downfall" without reform, while UEFA has launched disciplinary proceedings against those three clubs.
Al Mubarak issued an apology following Premier League champions City's run to the Champions League final, upstaged by English rivals Chelsea in Lisbon last week.
"I want to start with apologising to the fans," Al Mubarak told CityTV. "I owe it.
"It was a mistake. I think in hindsight, the decision should have been from the beginning: a decision not to participate in this league.
"I absolutely regret it. The benefit of hindsight is easy right now. I regret it and you can see it: our reluctance.
"It was very difficult. It was not an easy decision to say 'yes, no' and 'we're in' or 'we're out'.
"I think you can see in terms of the timing of when we actually did commit, it tells you a lot in terms of how challenging a decision it was and how much we struggled with that decision.
"But you can also see that once we recognise there was a mistake, that's it. We needed to go out immediately.
"I'm not going to sit here and defend the reason why we did it. What I will do is: I will own it. I took a decision ultimately on this and I take full responsibility, and it was a mistake."
Khaldoon Al Mubarak has expressed his sincere apologies to the Manchester City fans, admitting the Club made a mistake in agreeing to take part in the European Super League.— Manchester City (@ManCity) June 2, 2021
Watch part two of the Chairman's annual end of season interview
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After taking over City in 2008, Al Mubarak added: "We will continue to push the envelope in everything we do. We want to be the best club in the world and to do so, we have to disrupt and we will disrupt.
"In being disruptive, sometimes you make mistakes. We have made mistakes in the past, we will make mistakes in the future, but we will do more right than wrong.
"We will be better, stronger and more successful. What I tell the fans on this is, to get to where we are today we have done a lot of things right and we have made a lot of mistakes. It's part of growing and improving.
"You need to have the courage to make mistakes and to own up to these mistakes to go forward.
"If you go back 12 years ago where we started, to where we are today, we couldn't have done the leaps we have made over the years without taking risks and without making mistakes, learning and coming back and constantly improving."