Napoli fullback Christian Maggio has suffered a collapsed lung.
The Italy right-back missed Thursday's Europa League game with Porto because of a knock to the chest in training earlier this week, which proved to be far more serious than previously thought.
"From what the doctors tell me, the trauma happened on Tuesday before leaving for Oporto and on the plane back the situation became more complicated because of the altitude," agent Massimo Braschi told Radio Kiss Kiss Napoli.
"We will wait for Monday when there will be further tests."
