Milan won 3-0, with Gabbia impressing just days after signing a new contract.
Fonseca said afterwards: "I can say good things about Gabbia: he's a great professional.
"He's taking on an important leadership role, and he's playing very well. I told him that I'm very, very satisfied with his renewal: if there's a player who deserves it, it's him.
"Today we didn't concede and we didn't give Empoli any chances."
Alvaro Morata was back on the scoresheet and Fonseca said: "I've never been worried about Morata. I know Alvaro very well, he's an example for the team. Then it's important to score because it gives them confidence."
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