Atletico Madrid defender Filipe Luis has undergone a scan on an injured right hamstring that revealed a grade one tear.
The full-back did not take part in training on Friday after complaining of discomfort and was sent for medical examinations.
A brief Atleti statement read: "Filipe Luis didn't complete Friday 29 December's training session due to some discomfort. This Saturday, 30 December, the Brazilian left back underwent a medical exam.
"Filipe Luis was diagnosed with a grade one injury on his right hamstring.
"He will do physical therapy until he receives clearance from the medical staff."
Atleti did not say if Filipe Luis will miss any action, but reports in Spain suggest he is a doubt for the midweek Copa del Rey clash against Lleida Esportiu and next weekend's LaLiga contest against Getafe.
Diego Simeone's men are second in LaLiga after 17 matches, nine points adrift of runaway leaders Barcelona.