Ronaldo has been sidelined since testing positive for COVID-19 while on international duty with Portugal this month, missing Serie A draws with Crotone and Hellas Verona either side of a 2-0 victory over Dynamo Kiev.
🎙 @Pirlo_official: "For 15 years, Messi and @Cristiano have done great things. For the first time, I'll be taking on Messi as a coach, I'll treat him with the enormous respect that he deserves."#JuveBarça #JuveUCL— JuventusFC (@juventusfcen) October 27, 2020
The game at the Allianz Stadium would be the first time Messi and Ronaldo have gone up against one another in the competition since May 2011.
"He had a swab today [Tuesday] like everyone else. We have to wait for the outcome of the test. I think it will come in the evening," head coach Andrea Pirlo said.
"We have to wait for the result, then we'll see [if he will play]. For now, everything is still uncertain. We hope to be able to evaluate him even if it's not easy after 15 days of inactivity."
Pirlo also has concerns in defense, with Giorgio Chiellini and Matthijs de Ligt ruled out and Leonardo Bonucci facing a late fitness test.
"Tomorrow we will see what players we have available. Barcelona are strong and have great champions. We will have to play a great game," he said.
"The players will certainly have to sacrifice themselves and play a great game. [Weston] McKennie is training but I don't think he can play as a defender [against Barcelona].
"I'll continue with a back four because I only have four defenders."