Christian Pulisic had Milan ahead before halftime, with Raphael Onyedika sent off on 40 minutes for Brugge.
After the break, Brugge equalised via Kyriani Sabbe before Tijjani Reijnders scored twice for the 3-1 Milan win.
Afterwards, Fonseca played down his role in the win, which was influenced by his substitutions.
The double positive change: has Fonseca taken San Siro?
"The credit goes to the players and mainly to those who came on, who changed the match, changing our game, the intensity."
Good victory, but can't be satisfied with the first half?
"Obviously, in the first half, we didn't do things well. We were against a team with eleven very small players, then with an even smaller numerical inferiority. And we had difficulties in this type of game, in creating and provoking space. Then, when we don't find the right solution, the game starts to be too slow. When we don't find space, we need to have a different intensity in our actions. We didn't do well. The game was too slow. I think it was a problem of understanding the game."
What do you think of Rafael Leao's game?
"Offensively, Leao, in the first half, did important things for the team. Then I decided to change him, as I decided to change Loftus-Cheek. But for me this is normal. I wanted to be more incisive, more energetic in the corridors. For me there is no problem."
Camarda's debut?
"I'm very sorry for the disallowed goal. But it was a beautiful moment for the team, all on the pitch celebrating a child who works so hard. Camarda will have many opportunities to score more goals during his career."
What has changed in Okafor and Chukwueze?
"Confidence. They played a good match against Udinese."
What's happening to Loftus-Cheek?
"With me he played as an 8, as a 10, today as an attacking midfielder on the right. Loftus is a player who accelerates with the ball at his feet; when he doesn't have space, he has more difficulty. But it's not that he's afraid... Those are his characteristics. We need to make him understand certain things better. He works hard, always, he gives everything for the team. I'm sorry he wasn't at the level I know he can play at."
Should we keep Camarda in the first team?
"Mister Bonera, Mister Guidi and I do our best to help the youngsters grow. We have Morata, we have Abraham and Jovic, it becomes a bit difficult for Camarda to play. And at this age it is important to play. What we do is try to give him more space to improve, between the Primavera, Milan Futuro and the First Team. Sometimes it is more difficult to play in Serie C than in Serie A and vice versa. When he trains with us he does very well. Today he worked well for the team, with courage on the passing line. He doesn't seem like a boy of the age he is when he plays."