After winning the Confederations Cup, Neymar underwent surgery to remove his tonsils, an operation that could have reduced the iron levels in his blood.
The Brazilian is suffering from anaemia, which is when there is less than the normal quantity of haemoglobin in the blood. It is not an illness as such, but rather a condition which can be brought about by several things - usually an iron deficiency - and which reveals itself through symptoms such as exhaustion.
Neymar is currently being treated by the 'Azulgrana' doctors, and his father is concerned about his condition because the player has lost 7 kilos since the operation: "Neymar told me that he didn't feel his normal self. He told me that he feels exhausted after training sessions lately", said Neymar's dad, adding, "I think that the surgery brought on the condition".
"He's getting back to normal now. All the procedures that needed to be applied have now been performed", he concluded.