Napoli head coach Gennaro Gattuso will not risk Kalidou Koulibaly against Serie A leaders Inter, while Dries Mertens is also ruled out.
Koulibaly sustained a muscle injury during Napoli's 2-1 defeat to Parma on December 14 and had to be replaced five minutes into the game.
The centre-back was determined to return to face Inter but Gattuso will hold him back. However, Fabian Ruiz could be available after recovering from illness.
"I have great faith in all my players," Gattuso told a news conference. "Fabian will play if he is fit.
"Koulibaly wants to play but it's not right to risk him."
Of key forward Mertens' absence, Gattuso added: "In this week he only trained with the ball for three days. We decided yesterday morning [Saturday] to have him undergo an MRI.
"He has adductor swelling. We decided to send him to Belgium to his trusted man for treatment."
Napoli went into the mid-season break with a 2-1 win at Sassuolo secured by Pedro Obiang's last-gasp own goal.
"We did some good things against Sassuolo," added Gattuso, whose side are eighth in Serie A. "We need to keep doing what we're doing - we need time.
"Our first half against Sassuolo was embarrassing but we did well to stay in the game. Our quality in the second half won us the game.
"We mustn't look at the table. We need to take it game by game.
"My goal is to bring back the enthusiasm to the San Paolo."