Napoli are in a very good state now, even in their last game Ajax had to admit the advantage held by Napoli with a very landslide score. Napoli only needs one more win to be able to step into the knockout phase. Because with the addition of 3 points it is impossible for Ajax to catch up (if Napoli win in the second leg against Ajax). However if ajax wins the match then it will be hope for them. But I doubt that Ajax can win.
Napoli can already be said that they are actually in the playoffs, and this will most likely happen in the next match with Ajax. You see, they beat them away, and scored 6 goals against them, so the home game shouldn't be difficult for Napoli either. It may be that there will be some underestimation of the opponent and Ajax will play better, but I doubt that Napoli will allow Ajax to play even in a draw, Napoli need this victory to further focus on other tasks and most likely that they will be able to do it.