Cristiano Ronaldo, five times the best player in the world, will perform medical tests to determine an ankle injury. Italian champion Juventus said on Wednesday.
Ronaldo and Brazil Douglas Costa have been "trained" today, the club said in a statement on Sunday, the first "left foot suffered an injury after Bologna."
German coach Emre Jean and Albusni Miralim Pianic returned, while German midfielder Sami Khadira recovered after heart surgery.
Juventus lost 1-0 on Sunday and kept 13 points to win Napoli 4-0.
Ronaldo, Manchester United and Real Madrid star reached the tenth position of Serie A. With 19 successful matches, the goal of the Milan New York Christoph Ponentek and 21 goals has 34 games.
Juventus will take Second Division to recover two goals against Atletico Madrid on March 12.