Blatter made clear he preferred the Argentine over the former Manchester United ace during the Q & A on Friday.
In response to Real president Florentino Perez's written demand for an explanation, Blatter said:
"I received your letter earlier today and was surprised by the content contained therein.
"Firstly, I would like to point out that at the ceremony held last Friday at Oxford University, no discussions were held about the aspirations of any player with regard to the FIFA Ballon d'Or. At the end of my speech, and in response to a question about Lionel Messi and Cristiano Ronaldo, the moderator asked me to choose between the two and, at that moment in time, having stated that Messi is the kind of son that any mother would like to have, I finally gave his name. However, I would like to make it quite clear that it is my opinion that Cristiano Ronaldo is at the same level as Messi and that both are extraordinary players, each in his own way.
"I regret that this situation at a university ceremony has caused you so much distress and I would like to apologise for it. It was never my intention to cause discomfort or show a lack of respect to Real Madrid FC, one of it players or its support, not only because it is the founding club of FIFA but also because it is a club that I have followed and admired since I was a child.
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