Milan are expected to start the same XI that won the first leg of the Champions League quarter-final, but Luciano Spalletti admits to having one major doubt for Napoli as Victor Osimhen returns.
It kicks off at the Stadio Diego Armando Maradona on Tuesday at 20.00 UK time (19.00 GMT).
The away goals rule no longer applies, so if the Partenopei win by one clear goal, it will go to extra time.
Stefano Pioli has a full squad to choose from, as Olivier Giroud has shaken off a bruise, so it seems inevitable that he will field the same XI that started at San Siro last week with Rafael Leao and Brahim Diaz.
As for Napoli, they welcome Osimhen back to the start for the first time since he sustained a muscular injury on international duty with Nigeria in March.
However, Andre Frank Zambo Anguissa and Kim Min-jae are both suspended, so that means at least three changes with Osimhen stepping in.
Juan Jesus is almost certain to step into defence, especially as he was chosen to speak next to Spalletti in today’s press conference.
Anguissa is more complicated, as the coach admitted today he is considering the options between Tanguy Ndombele and Eljif Elmas.
The other question marks are left-back between Mathias Olivera and Mario Rui, while either Matteo Politano or Hirving Lozano will complete the trident attack with Osimhen and Kvicha Kvaratskhelia.
Giovanni Simeone is on the treatment table after a thigh strain.
Probable line-ups
Napoli (4-3-3): Meret; Di Lorenzo, Rrahmani, Juan Jesus, Mario Rui; Ndombele, Lobotka, Zielinski; Politano, Osimhen, Kvaratskhelia
Milan (4-2-3-1): Maignan; Calabria, Kjaer, Tomori, Theo Hernandez; Tonali, Krunic; Brahim Diaz, Bennacer, Leao; Giroud