The 17-year-old has reportedly been the subject of a $20 million (£10m) offer from the Champions League winners and is expected to move when the Brazilian season ends.
Pato's father Geraldo da Silva, also his representative, said he expects a deal to be completed within a fortnight.
"We have put a deadline on deciding what will happen with Pato," he said.
"All the speculation and rumours linking him with European teams is very strong, so in the next two weeks everything will be resolved."
Meanwhile Internacional president Vitorio Piffero, however, denied there is a concrete agreement in place with Milan.
"There is no truth in reports that Milan representatives will be coming here to watch Pato. It's all speculation," he said.
"I understand that there will be speculation about a player of this quality, but it is all speculation."