You won't fault Piatek for his effort and sharpness. He moves all over the pitch and often quite cleverly, ghosting in to the right spots. And if he gets the ball where he wants, he rarely misses. He's a poacher in the sense he's as good as any poacher inside the box. But he's not a poacher in the sense he roams far more than usual poachers do. Which suits our style of play.
However, doing the same for Milan will be a different ball game. Naturally, defences will be more alert and more in numbers against us than against Genoa, and we'll need to see how he copes.
I'd definitely play two wing forwards and Paqueta along with him to give him adequate space. ie Calhanoglu, Suso, Paqueta and Piatek should be the 4 guys attacking the box.