Milan won 3-1 with goals via Alexis Saelemaekers, Luka Jovic and Tijjani Reijnders.
Fonseca said afterwards: "We’ve only had five weeks of work, there’s a long way to go. We can already look at some of the team’s intentions that they’re already trying to put on the field.
“Today we played with two different teams, we have different things to improve and work on. I’m very satisfied because the players are trying to do what we’ve been working on in these weeks.
"I’m happier with the offensive phase. It’s been five weeks of work, it’s a different way of playing defensively too. I’m not making comparisons, I’m just saying it’s different.
“We need time to improve defensively. If we want to be a team that presses high there are things to improve. In the first 20 minutes we did well, we recovered high balls. We need time to continue improving.”
On Rafael Leao, he said: “We are working together, I am very satisfied. It seems to me that Rafa is more inclined to work for the team defensively. I am sure he will be a different player.”
And on goalscorer Saelemaekers, Fonseca added: “He is a team player, he can do different roles well. He works a lot defensively for the team, offensively he brings important things. I like him a lot, I would like him to stay in the team.”