Ronaldo is being asked by police to provide a DNA sample in an investigation of the allegation by Kathryn Mayorga, a former model and schoolteacher, that he raped her in his Las Vegas hotel penthouse in 2009 and paid her to keep quiet.
Speaking in a pre-match news conference, Allegri said “Ronaldo’s case is a private matter. I’ve seen him very calm.”
Allegri added that Ronaldo will play in an Italian Cup match at Bologna on Saturday: “He’ll play tomorrow. We’ll see about when and how.”
The Portuguese has enjoyed a fine start to his career at the Allianz Stadium since signing from Real Madrid for £89 million last summer.
The 33-year-old has 15 goals and eight assists in all competitions so far with the Old Lady aiming to finally break through in Europe.
Juve will face Atletico Madrid in the last 16 but will first aim to consolidate their place at the top of Serie A in pursuit of an eighth straight title.
There is also next week’s Supercoppa against Milan, taking place in Jeddah, Saudi Arabia, following their clash with Bologna.