Alexandre Pato's arrival at Chelsea last week was delayed for about 24 hours due to some "complications" regarding the financial arrangements of his loan.
One such complication was a weird clause supposedly inserted by Pato's parent club Corinthians, to basically force any club in England, not just Chelsea, to pay a fee in order to acquire Pato in the summer. There were also rumors that Corinthians were trying to further protect themselves against losing Pato without any compensation by making him sign a new contract extension before agreeing to this loan. However, according to Corinthians President Roberto de Andrade, neither of those stories are exactly accurate.
"We did not make the extension, the athlete did not. It was an idea of mine, I insisted on it. We made the loan with option to buy in June. I believe that if he [plays well], Chelsea will honor. If he does not, he returns to Corinthians."
-Roberto de Andrade; source: Globo via Google Translate
De Andrade also claims that there is no penalty fee that would need to be paid by other (non-Chelsea) English clubs if they wanted to sign Pato on a pre-contract in the summer. The only agreed fee at this point is with Chelsea, to the tune of €12m. Corinthians realize that this could very well mean that they lose Pato on a free eventually, but at least they're saving on their wage commitment, which is paid fully by Chelsea during the loan.