Milan are among the form teams of Serie A, though were beaten in the Champions League at Bayer Leverkusen in midweek.
Fonseca said: “Continuity is important at this point. It’s important to have extra days for the players to recover if the team is doing as well, and to keep as many players in the starting line-up as possible. It’s not because I don’t have faith in the players.
“Loftus-Cheek and Chukwueze have come in, done well and are working hard, but I think it’s important to have a base to start from.
“There’s still a lot to play for, and there are many strong teams that have the same objective as us. Obviously Napoli has the advantage of not playing in the European cups. They have a very strong coach and a very strong team. I’m not trying to put pressure on them, it’s the truth. Napoli is a real candidate for the Scudetto.
“We are in a time of growth. It’s not the case that we’ve made it because we won against Lecce and Inter, we need to carry on growing. We are improving, but we have a lot to improve on still. The real Milan is not close yet, we have to do more.”