Jose Gimenez is a major doubt to feature for Atletico Madrid on Sunday after the club said the defender is suffering from a muscle infection.
The 22-year-old has missed the past two training sessions while being treated with antibiotics.
"Jose Maria Gimenez could not train with his teammates in the last two sessions due to 'an infection in the subcutaneous cellular tissue of the right leg, which does not affect joints nor other structures,'" Atletico said in a statement.
"The Uruguayan defender is undergoing a shock treatment with antibiotic to attack the infection."
Atletico are already without Diego Godin, who could miss two weeks with a thigh injury, while Lucas Hernandez has been caught up in legal proceedings since his arrest in a domestic dispute last week.
That leaves Stefan Savic as the loan centre-back available to face Celta Vigo this weekend, with Atletico fourth in the table.