Michael Platini has formally declared that he no longer supports Sepp Blatter as FIFA president, saying the world governing body needs "a breath of fresh air".
UEFA president Platini was a strong supporter of Blatter's in the past but believes it was wrong of the 78-year-old to go back on his word to stand down in 2011.
Platini, in Sao Paulo ahead of the opening match of the World Cup, said: "I do not support him. I have known him for a long time and I like him but I am not in favour of him having a new term.
"I supported him in 1998 but I do not support him in 2014. And in the future I will not support Mr Blatter.
"I told him. I think that FIFA needs a breath of fresh air.
"In 2011 he asked for our support [UEFA's] and told us that that would be his last term..."
Platini said it was still an possibility that he would run against Blatter but he would not decide until the end of August.
He added: "It is an option. But it is not because Blatter is running that Michel Platini will not run. And it is not because Blatter is not running that Michel Platini will run.
"My only concern is knowing what I want to do. I am 60 soon and I need to know what I want. I will take my time."
Platini said he also had to think about the impact on his family if he went for the FIFA position.
He said: "It is not just mine but also that of my family, my children. That's a lot of people. But choosing between UEFA and FIFA is not choosing between going to hospital or going to prison - the choice is not a negative one. But when I launch, it is to win."
Blatter was infuriated by the reception he received from UEFA federation members, including Football Association chairman Greg Dyke, earlier this week.
Dyke had told Blatter at a meeting of UEFA countries on Tuesday his claim that racism was behind World Cup corruption allegations in the British media was "offensive and totally unacceptable".
Blatter told a news conference after the FIFA Congress in Sao Paulo: "I have had to accept a number of blows, but what I saw and heard at the UEFA meeting was the most disrespectful thing I have experienced in my entire life, on the football pitch and in my home."
Blatter's position has been hugely strengthened, however, after FIFA delegates defeated moves to bring in term limits and age limits for officials. It effectively gave the green light for Blatter to stand for re-election next year.