Both goals came via veteran striker Zlatan Ibrahimovic.
“When a team is in good shape mentally, the legs and body go along with the mind," Pioli told Sky Sport Italia.
“We did well against a very aggressive, intense opponent, and I thought up until the second goal we were doing very well, creating chances and pressing. There are areas where we need to improve once we've taken the lead."
Ibrahimovic has scored three of the four goals so far this season, with Hakan Calhanoglu getting the other.
“When the team works, the individuals inevitably raise their game too. Zlatan is a champion and confirms that every time he steps on to the pitch, even in training.
“The side plays with confidence, can grit its teeth under pressure and fight hard. The tactical mechanisms are working well.
“These are still largely quite young players and therefore have a lot of potential to get stronger. There's a lot of quality in the side, they just need to learn more how to read the game, when to attack and when to soak up pressure."