The soccer superstar has been accused of rape in the United States.
But his hero's welcome to the club where he made his name could be overshadowed by the allegation of rape by Kathryn Mayorga after they met in a Las Vegas nightclub in 2009.
Ronaldo, 33, denies the allegations.
Nemanja Vidic described Cristiano Ronaldo as the flawless role model as the Manchester United great returns to Old Trafford with Juventus.
"I enjoy football, my life". Of course, the truth is always coming in the first position.
The five-time world player of the year had previously confronted the allegations in an Instagram video on 3 October, hours after the lawsuit was filed.
Former United defender Vidic spent three years playing with Ronaldo and he hailed the five-time Ballon d'Or victor ahead of his return to the Theatre of Dreams. Attorneys for Mayorga have challenged Ronaldo's legal team to prove that documents are false.
His spectacular overhead kick for Real Madrid against Juventus was overlooked in favour of a Mo Salah strike, but Ronaldo insisted he is not concerned about the snub.
"I know I'm an example". "I know, 100 per cent". On the pitch and outside the pitch. I am very happy. I'm blessed that I play at a fantastic club.
"So the rest, it doesn't interfere on me", he added, before saying with a smile: "I'm very, very well".
Even with his reputation on the line, Ronaldo will be afforded a hero's reception from both sets of fans when he emerges from the tunnel, just as he was on his last visit to Old Trafford, with Real Madrid in 2013.
The five-time Champions League victor spoke to the media ahead of tomorrow's encounter and was asked about the allegations at the end of the press conference.
Ronaldo's goal was the lone score of the first half.
A run of four wins from their first nine Premier League games also does little to suggest they are likely to inflict Juve's first defeat of the season. The support is fantastic and Alex Ferguson is someone I will never, ever forget. (Then-United manager) Sir Alex (Ferguson) is someone I will never forget.