The 35-year-old first tested positive exactly a fortnight ago and he was forced into a self-isolation for a period of two weeks.
Juventus take on Barcelona in Turin on Tuesday and audiences had hoped to see Ronaldo come up against Lionel Messi for the first time since the former Manchester United striker left Real Madrid in 2018.
However, Ronaldo tested positive again today for Covid-19 and he will be denied the chance to come up against the Argentine.
Though Ronaldo has completed the mandatory self-isolation time, players must return a negative test in order to play again.
Ronaldo has missed three matches so far due to the virus: one with Portugal and two with Juventus.
It means Juventus will be without their main man as they look to challenge Barcelona for top spot in the group.
Barcelona were beaten by arch rivals Real Madrid at the Nou Camp on Saturday and Josep Bartomeu has today resigned from the club’s board following months of speculation.