The game kicks off on Saturday at 19.45 UK time (18.45 GMT).
Coach Vincenzo Italiano named his squad and it includes Erick Pulgar, Lucas Martinez Quarta and Nicolas Gonzalez.
However, they are still not back in Italy after international duty with Chile and Argentina.
According to Radio Bruno, their flight was delayed by three hours, which will then have a knock-on effect for the connecting flight they were meant to take from Madrid to Italy.
The match is played in Bergamo at the Gewiss Stadium.
Fiorentina squad for Atalanta: Amrabat, Benassi, Biraghi, Bonaventura, Callejon, Castrovilli, Igor, Dragowski, Duncan, Gonzalez, Kokorin, Maleh, Martinez Quarta, Milenkovic, Nastasic, Odriozola, Pulgar, Rosati, Saponara, Sottil, Terracciano, Terzic, Torreira, Venuti, Vlahovic