Tuchel noted that it will be a “matter of hours” to decide if Mount makes the trip or not.
The England midfielder missed Saturday’s loss to Manchester City due to a “minor knock”.
Mount has not recovered sufficiently enough for Tuchel to rely on his presence against the Serie A giants.
“I absolutely don’t know, we have to see.
“In the end it will be a matter of hours as to whether he makes it or not,” Tuchel told Chelsea’s website.
The Blues defeated Zenit 1-0 in their opening group game on Match Day 1.