Real Madrid defender Pepe is facing a race to be fit for the Champions League final against Atletico Madrid.
The Portugal centre-back underwent tests on his calf injury on Friday where it was confirmed he had suffered a strain.
A Madrid medical statement read: "After receiving imaging tests today in the Hospital Sanitas La Moraleja, Pepe was diagnosed with a grade 1 injury in the soleus muscle of his left leg. The player's progress will be monitored."
Madrid did not announce how long Pepe is expected to be out for, but reports in Spain suggest he could be sidelined for 15 days.
That would rule the 31-year-old out of Madrid's final two Primera Division games against Celta Vigo and Espanyol, and make him a major doubt for the Champions League final against Atletico on 24 May.