Barcelona says Lionel Messi has a fever and did not attend Wednesday's scheduled training session.
The club says Messi, who played a lackluster match in his team's 3-1 loss to Real Madrid in the Copa del Rey semifinals on Tuesday, was being attended to by doctors.
Barcelona says "a team of doctors have visited Messi at home, where he has been given appropriate medication and been advised to rest."
The club says midfielder Xavi Hernandez also missed Wednesday's training session, instead doing "physiotherapy work."
Messi hit the outside of the far post early in the match at the Camp Nou but was then effectively neutralized by Madrid's midfield. Cristiano Ronaldo scored two goals for Madrid.