The Portuguese star, who is the more prolific scorer in the history of the competition, hasn't featured in it yet this season after testing positive for coronavirus.
During his quarantine, he missed the win over Dynamo Kyiv and, more crucially, the defeat against Barcelona.
After being given the all-clear with a negative test this weekend, he came off the bench for Juve against Spezia and it was like he had never been away, scoring two goals.
Alvaro Morata will be the likely player to make way if Ronaldo starts against Ferencvaros, with Dejan Kulusevski and Paulo Dybala in behind supporting.
Merih Demiral is suspended for the game after being sent off against Barca, but Giorgio Chiellini should be available to make his return after a couple of weeks out to partner Leonardo Bonucci and Danilo in defence.
Matthijs de Lift and Alex Sandro probably won't return until after the next international break.
Juan Cuadrado and Federico Chiesa will likely take the wide positions, with Rodrigo Bentancur and possibly Adrien Rabiot in beside the Uruguayan in central midfield.