Ronaldo tested positive for COVID-19 while on international duty with Portugal and had to undergo the mandatory self-isolation, putting him in doubt for the fixture against the Catalans.
The 35-year-old has now tested positive in a second test conducted, and with less than a week to go until the marquee fixture, it looks all but likely that he would have to sit out the Group G match.
The two sides are among the contenders for the European crown and are expected to battle it out for the top spot in their group.
Lionel Messi was among the goals, opening the scoring from the spot as Barcelona ran riot in a 5-1 victory over Hungarian champions Ferancvaros in their group opener. An Alvaro Morata brace gave Juventus a 2-0 away win over Dynamo Kyiv.
Lionel Messi opens up on relationship with Cristiano Ronaldo and wishes him good health
The rivalry between Lionel Messi and Cristiano Ronaldo in the last 15 years has been well-documented, and together, the pair have rewritten football history with their exploits on the field.
They have both set records, too numerous to list, and they are both regarded as the best players in the history of the game. The competition between the two players has led to the media speculating that they have a personal rivalry, although both men have sought to clarify that this is not the case.
Lionel Messi was interviewed by DAZN ahead of Barcelona's El Clasico clash with Real Madrid and he touched on the Ronaldo issue and the upcoming fixture against Juventus.
"The one with Cristiano Ronaldo was and is a special duel, which will remain forever. It lasted many years and it is not easy to maintain certain levels for a long time," said Lionel Messi.
"Our teams were also very demanding: Real Madrid and Barcelona, the two strongest clubs in the world. Competing as equals for so many years is something that will remain forever. The duel between me and Cristiano Ronaldo was very good on a personal level and I think people enjoyed it."
He also weighed in on the possibility of both men sharing a pitch sometime in the future, saying:
''Obviously, when Cristiano played for Real Madrid, the games against them were always special. With Cristiano on the pitch, they had a particular meaning. It is now in the past, we look forward to today's challenges. We hope that Cristiano can be there and will recover soon from COVID-19," said Lionel Messi.
Lionel Messi will turn his attention to the clash with Real Madrid this weekend before traveling to Turin to take on Juventus, who will be hampered by the absence of Cristiano Ronaldo.Published 23 Oct 2020, 19:14 IST