Pato has been linked with Chelsea, while he will watch the World Cup from home after being left out of Brazil's squad.
"Will I miss Leonardo? With him, I learned a lot. He did a lot of work here at Milan, but his choice must be respected," said Pato. "The injury has affected me. But I've always believed in myself.
"I will work to play in the World Cup of 2014 in Brazil."
He added: "Next season, I will score 20 goals."