Portugal great Eusebio is in hospital after displaying early symptoms of pneumonia, according to officials at his past club Benfica.
The Portuguese club said in a brief statement that Eusebio, 69, has been admitted to Lisbon's Hospital da Luz. It gave no further details.
The Portuguese Football Federation said it had no official information.
Eusebio scored 41 goals in 64 games for Portugal and has since been a football ambassador for Benfica and Portugal.
He was born in Mozambique when it was still a Portuguese colony, and became known as the "black panther" for his powerful performances in the 1960s for Benfica and the Portuguese national team.
Eusebio won 10 league championships, five Portuguese cups and one European Cup in his 15 years at Benfica and was Portugal's top league scorer between 1964 and 1973.
"Benfica wish a speedy recovery to the Black Panther," read the statement on the club's official website.