Napoli currently sit top of the Serie A table ahead of Inter Milan and Atalanta.
Reja told Radio Kiss Kiss: "I think we need to prepare the fourth star, I saw a solid Napoli, they are a confident team, they know what they want and prepare it well. Let's not forget that Atalanta is strong, but the feeling is that as soon as the opponent makes a mistake Napoli punishes you, then there is a defensive solidity to appreciate.
"Napoli is a strong team and now they are starting to have certainties. They will always improve. It's one thing to play 35 games, another to play 55. If you manage the substitutions it can be done, it also depends on the type of game they play, Napoli has a way of playing based on the defensive phase.
"Inter, which is the team most accredited for the Scudetto, has to face many situations with the Cups, you can also see it from the injuries they are suffering."