Brazil World Cup winner Ronaldo is in intensive care in Ibiza suffering from pneumonia.
The 41-year-old former striker tweeted that he was taken ill on Friday but hopes to be discharged on Monday.
Ronaldo scored 62 times for Brazil, including both goals when they beat Germany in the 2002 World Cup final.
The former Real Madrid forward, who also played for Barcelona, Inter Milan and AC Milan, thanked his fans for their love and well wishes.
A spokesperson from Can Misses Hospital, where Ronaldo is being treated, said she was unable to give any information for privacy reasons.
Ronaldo was on holiday in Ibiza, where he owns a home.
The striker’s career ended seven years ago when he hung up his boots up after two years with Corinthians in Brazil.
Among those sending best wishes to Ronaldo were former Manchester United and England defender Rio Ferdinand, who tweeted a picture of the two of them together with the message: “Just seen the news… hope you’re OK legend Ronaldo – get well soon!”