Portugal legend Eusebio is to stay in hospital in Poznan until Thursday owing to high blood pressure, the national team doctor Henrique Jones says.
Jones had indicated on Sunday that the star of Portugal's run to the 1966 FIFA World Cup semi-finals might be able to leave earlier but said on Monday he will stay put for now.
Eusebio fell ill on Saturday at the team hotel, and Jones explained after visiting the 70-year-old 1965 Ballon d'Or winner: "He will rest for a couple of extra days and probably be allowed out Thursday.
"Although his state of health would allow him to leave hospital, it has been decided he will be taken out by hospital plane. It's just an understandable precaution."
It is the fourth time this year that the 70-year-old 1965 Ballon d'Or winner has been hospitalised.
On Sunday, Jones had said: "He is stable. He was joking and speaking with us. He should be up to leaving hospital tomorrow (Monday)."
Portugal is set to play defending European champion Spain in its EURO 2012 semi-final at Donetsk, Ukraine.
But Jones said on Sunday: "Given the status of his heart, it is preferable that he doesn't stay for the match against Spain."
He added Eusebio had had a number of tests, including an electrocardiogram, which revealed 'some small variations'.
Eusebio, born in the former Portuguese colony of Mozambique, made his name with Benfica, with which he won a string of domestic and international trophies including the 1962 European Cup.
The Black Panther was also instrumental in Portugal finishing third in the 1966 World Cup where he also top scored with nine goals.
Apart from winning the Ballon d'or he was twice the leading European goalscorer.
Gibraltar, the tiny British overseas territory boasting just one professional player, will take part in the EURO 2016 qualifying campaign after gaining UEFA membership - but will be kept apart from Spain.