Napoli's upcoming matches in Serie A will have a level of quality of opponents that are more difficult than what Milan will face. Juventus and Inter have recently seen their form improve with successive wins in Serie A, one mistake from Napoli will give the way for Milan to further destabilize Napoli's position in the standings.
Can Milan defend their Serie A title with only half a season remaining?
It is still very possible for AC Milan to defend the Scudetto title this season as long as they can play consistently and win one match after another. It also depends on Napoli's performance, if Napoli declines in terms of performance and loses point after point then that will increase the chances for AC Milan to take over the position now occupied by Napoli. But with Napoli doing well so far, I have a feeling they won't miss the excellent opportunities they have now. Napoli are 8 points away from AC Milan and it will be very difficult for AC Milan to catch up, especially since a big game awaits them in the second half of this season.