I think it will be very difficult to predict the result of this match. Milan has been playing well against Napoli recently, they beat them recently in the Italian championship even 4:0 at home, but this is still a different game, the most important game of the season for both teams.
Napoli is playing at home and their main striker Osimhen is back, which gives them a slight advantage in return.
On the other hand, Napoli will be under a lot of pressure and if Milan impose their game, like in the championship game, then it will be very difficult for Napoli.
In the first game, Napoli missed an opportunity for a much better result, and now a lot will depend on who will score the first goal.
If in the first leg Milan has a high probability of winning, then in the second leg the probability shows that Napoli is the favourite. I think it's influenced by the return of their best striker, but in any case Milan still has a chance to hold Napoli to a draw at least. Whoever scores the first goal I think they will win, and I think this is one of the plans that Luciano Spalletti is very likely to hope for tomorrow.
The pressure is on for Napoli, they haven't won 2 match in a row at home recently including against Verona yesterday. Even though Osimhen played in that match as substitute, Napoli still failed to win the match which ended 0-0.