It kicks off in Leipzig on Monday at 20.00 UK time (19.00 GMT).
A point would suffice to send the Azzurri through to the Round of 16 in second place behind Spain, whereas Croatia need a victory to qualify after one point from the opening two games.
Coach Luciano Spalletti was already planning several changes to the side that beat Albania 2-1 and then lost 1-0 to Spain, but another is certainly forced upon him, as Dimarco did not train today due to a bruised right calf.
A statement from the FIGC noted his condition was being evaluated on a day-to-day basis, so he is not going to be fit to start on Monday evening.
With that in mind, it also makes it less likely that Spalletti could shelve the four-man defence for three, considering Dimarco’s surges forward were a big part of those moves at Inter in a 3-5-2.
He would then be replaced in the middle of the defence by Gianluca Mancini with Alessandro Bastoni, while Matteo Darmian is expected to come in on the right.
In midfield, Jorginho could be dropped in favour of either the more defensive Bryan Cristante or creative Nicolò Fagioli to partner Nicolò Barella.
Considering the strength and experience of the Croatian midfield, he might not want to launch Fagioli into that battle.
Federico Chiesa and Gianluca Scamacca have not given their best so far and are facing competition from Mattia Zaccagni and Mateo Retegui.
(4-2-3-1): Donnarumma; Darmian, Bastoni, Mancini, Calafiori; Barella, Cristante; Chiesa, Frattesi, Zaccagni; Retegui