Napoli choose Giovanni Simeone and Kvicha Kvaratskhelia with Piotr Zielinski out of a 3-4-3 formation, while Fiorentina have Lucas Beltran and Jack Bonaventura.
It kicks off at the Al-Awwal Park in Riyadh at 19.00 GMT.
You can follow all the build-up and action as it happens on the LIVEBLOG.
The winner will be decided tonight after 90 minutes or go straight to a penalty shoot-out, without extra time.
This Final Four format has the Scudetto winners Napoli and Coppa Italia holders Inter, but also the runners-up for those two tournaments, Lazio and Fiorentina, then the Final is on Monday.
Walter Mazzarri is missing Victor Osimhen and Andre Frank Zambo Anguissa at the Africa Cup of Nations, while Alex Meret, Mathias Olivera, Diego Demme and Natan are all injured.
The surprises are that Zielinski is on the bench, perhaps because of his refusal to sign a new contract, while Mazzarri seemingly moves to a 3-4-3 formation thanks to new signing Pasquale Mazzocchi.
Simeone gets the nod upfront rather than Giacomo Raspadori with Kvaratskhelia.
Fiorentina have Christian Kouame on international duty, Nico Gonzalez, Gaetano Castrovilli and Dodo injured.
Marco Davide Faraoni impressed on his debut after the move from Verona, but is on the bench, while Beltran is chosen ahead of M’Bala Nzola.
Vincenzo Italiano has been testing out a variant three-man defence lately and that could still happen during the game.
When these sides met in October, Fiorentina emerged 3-1 winners.
Napoli: Gollini; Di Lorenzo, Rrahmani, Juan Jesus; Mazzocchi, Cajuste, Lobotka, Mario Rui; Politano, Simeone, Kvaratskhelia
Napoli bench: Contini, Idasiak, Zerbin, Zielinski, Lindstrom, D’Avino, Ostigard, Gioielli, Gaetano, Raspadori
Fiorentina: Terracciano; Kayode, Milenkovic, Martinez-Quarta, Biraghi; Arthur, Duncan; Ikoné, Bonaventura, Brekalo; Beltran
Fiorentina bench: Martinelli, Vannucchi, Christiansen, Sottil, Maxime Lopez, Ranieri, Nzola, Infantino, Faraoni, Comuzzo, Mandragora, Parisi, Barak, Amatucci
Ref: La Penna
VAR: Aureliano
More must-reads:
Get the latest news and rumors, customized to your favorite sports and teams. Emailed daily. Always free!