He first tested positive on October 13 while on international duty with Portugal, although the forward has been symptom-free.
There has been some confusion as to whether it is already too late for Ronaldo to be in contention after his latest positive. But Sky Sports, among others, say there is still a small chance Ronaldo could feature.
According to several reports, should he test negative 24 hours before the Barcelona clash, which is on the 28th, he could be available for the match.
Ronaldo returned to Italy after testing positive, which the country’s sports minister says could have been a violation of health protocols. However, Juventus maintains no rules were broken.
This would be his first meeting against a team starring Lionel Messi since Ronaldo left Real Madrid. The much anticipated clash will still be hugely important in determining the group winner whether the Portuguese superstar features or not.