Milan are chasing the Santos star for the summer market.
Robinho said: "I don't know if Ganso is physically ready for European football yet, but he has amazing technique. After all, Alexandre Pato took a while to develop his strength when he first came here.
"With his quality feet, Ganso could help us win the Champions League. He has to come as soon as possible, because playing in Serie A is very different to Brazil."