Cassano's switch from Sampdoria is due to be rubberstamped in hours.
Pato declared: "He's a great player who will give us great help to try to win. Together, we will have fun and do very well. I'm happy for his arrival, it's like having another Brazilian on the team.
"His arrival could mean the departure of Ronaldinho? I see him being calm and I've never heard him complain.
"I want him to stay and I'm sure he wants to stay. We just have to respect the choices from our coach."