Doctors say former Portugal and Benfica star Eusebio is likely to stay in a hospital over Christmas after being diagnosed with double pneumonia.
Joao Sa, head of the intensive care unit at Lisbon's Hospital da Luz, said late Wednesday that doctors are optimistic about Eusebio's chances of a full recovery.
But he said the illness requires close monitoring and Eusebio will undergo treatment for several more days.
Eusebio da Silva Ferreira, who turns 70 next month, became a national icon after his standout performances in the 1960s for Benfica and the Portuguese national team.
He was named one of the 10 best football players of all time by FIFA in 1998.