If Osimhen will return to play i think this is a good news for Napoli because at least with Osimhen their chances to win the match is quite bigger when they playing without him and actually Atalanta is not strong opponent for Napoli because during this season Atalanta has several times to lose against tough teams just like Inter Milan or Fiorentina so if Napoli can able to performing well then beat Atalanta isn't hard for them
But the most problem is Napoli will play with their new manager Walter Mazzarri so i think all of the players will be required to adapt with Mazzarri strategy so it won't be easy for them to beat Atalanta however i found interesting fact for this match because for betting options the bookmakers provided equal odds for both teams @2.60 which mean this is hard match for them
I heard was like that, so indeed Napoli victory in that match increased with Osimhen. And there shouldn't be any problems because they attack line will be sharp again, but considering they have a new tactician then the results may not be as expected. Because yes their squad must be able to adapt to the new tactician, even though experience Mazzarri is not too bad and the Napoli squad is also not too bad because they have many quality players. But the match against Atalanta is his first match in Napoli this season, so it won't be easy for him.