Former International Olympic Committee president Juan Antonio Samaranch is gravely ill with severe heart problems.
A spokesman for the Barcelona hospital where the 89-year-old is being treated said his condition is "very serious".
The Spaniard was widely regarded as the most powerful man in sport when he headed the IOC from 1980 to 2001.
An astute figure on the global stage, he oversaw the commercialisation of the Olympics as athletes were finally allowed to embrace professionalism.
Only Pierre de Coubertin, the "father" of the modern Olympics and IOC chief from 1896 to 1925, held the post for a longer period.
Samaranch, the IOC's honorary life president, was admitted to Barcelona's Quiron Hospital on Tuesday.
Chief of internal medicine Rafael Esteban said he is under observation for "acute coronary insufficiency".
"He is currently in intensive care and his prognosis is very serious," Esteban added.
"We can't be optimistic because of the acute condition and the advanced age of the patient.
"At the moment he is stable, but the risk is high during the first 48 hours. We fear for his life."
Samaranch has suffered several health problems in recent years.
He spent 11 days in hospital in Switzerland with fatigue in 2001 after returning from an IOC session in Moscow, where Jacques Rogge was elected as his successor.
Samaranch was also treated in a Monaco hospital in September because of a slight reaction to fatigue, and spent two days in a hospital in Madrid in 2007 with high blood pressure.
He has also received dialysis treatment for kidney trouble.
Born in Barcelona on 17 July 17, 1920, Samaranch enjoyed success as a roller-skater and led the Spanish team to the world title.
He pursued a career in sports politics in dictator Francisco Franco's fascist Spain and won a place on the IOC in 1966.
After Franco's death, Samaranch was appointed ambassador to the Soviet Union and the contacts he made there helped him succeed Lord Killanin as IOC president in 1980.
In recent years, he was a key part of Madrid's failed bids to host the Olympics in 2012, which London eventually won, and 2016, which went to Rio de Janeiro.
"I know that I am very near the end of my time. I am 89 years old," he said in October 2009 before asking the IOC members for the honour of hosting the 2016 Games in Spain during Madrid's bid presentation in Copenhagen.
A spokesman for the Barcelona hospital where the 89-year-old is being treated said his condition is "very serious".
The Spaniard was widely regarded as the most powerful man in sport when he headed the IOC from 1980 to 2001.
An astute figure on the global stage, he oversaw the commercialisation of the Olympics as athletes were finally allowed to embrace professionalism.
Only Pierre de Coubertin, the "father" of the modern Olympics and IOC chief from 1896 to 1925, held the post for a longer period.
Samaranch, the IOC's honorary life president, was admitted to Barcelona's Quiron Hospital on Tuesday.
Chief of internal medicine Rafael Esteban said he is under observation for "acute coronary insufficiency".
"He is currently in intensive care and his prognosis is very serious," Esteban added.
"We can't be optimistic because of the acute condition and the advanced age of the patient.
"At the moment he is stable, but the risk is high during the first 48 hours. We fear for his life."
Samaranch has suffered several health problems in recent years.
He spent 11 days in hospital in Switzerland with fatigue in 2001 after returning from an IOC session in Moscow, where Jacques Rogge was elected as his successor.
Samaranch was also treated in a Monaco hospital in September because of a slight reaction to fatigue, and spent two days in a hospital in Madrid in 2007 with high blood pressure.
He has also received dialysis treatment for kidney trouble.
Born in Barcelona on 17 July 17, 1920, Samaranch enjoyed success as a roller-skater and led the Spanish team to the world title.
He pursued a career in sports politics in dictator Francisco Franco's fascist Spain and won a place on the IOC in 1966.
After Franco's death, Samaranch was appointed ambassador to the Soviet Union and the contacts he made there helped him succeed Lord Killanin as IOC president in 1980.
In recent years, he was a key part of Madrid's failed bids to host the Olympics in 2012, which London eventually won, and 2016, which went to Rio de Janeiro.
"I know that I am very near the end of my time. I am 89 years old," he said in October 2009 before asking the IOC members for the honour of hosting the 2016 Games in Spain during Madrid's bid presentation in Copenhagen.
