The Croatian midfielder picked up a nasty ankle injury following a horror tackle from Leeds United's Daniel James in midweek and had to be taken off after 30 minutes at Elland Road.
Kovacic injured the same ankle in the FA Cup semi-final win over Crystal Palace, and he was set to join Ben Chilwell and Callum Hudson-Odoi on the sidelines for the final, but there is now a slim chance that he could be involved.
Tuchel has claimed that there is a "90% chance" of Jorginho and Ruben Loftus-Cheek pairing up in the middle amid N'Golo Kante's fitness woes - whether that is simple mind games remains to be seen, with Kante expected to be fit enough to play some part at the weekend.
Mason Mount produced a man-of-the-match showing at Elland Road and will hope to keep the momentum going on Saturday, where Romelu Lukaku will hope to have done enough to warrant a start following his recent upturn in fortunes.
Chelsea possible starting lineup: Mendy; Azpilicueta, Silva, Rudiger; James, Jorginho, Loftus-Cheek, Alonso; Mount; Havertz, Lukaku