Argentine football legend Diego Maradona, who has a history of drug abuse and weight problems, was fighting for his life in critical condition in hospital here Monday after suffering acute heart failure.
Dozens of his fans held a vigil in front of The Swiss-Argentine clinic, praying for their fallen star.
The hospital said in a statement that the 43-year-old former captain of the Argentine national team was unable to breathe by himself.
His doctor, Alfredo Cahe, told reporters that Maradona's reaction over the next 24-48 hours would be crucial to his recovery chances.
Buenos Aires swirled with rumours about the cause of the illness, with the TN television channel saying Maradona's plight stemmed from a drug overdose.
Considered one of the greatest footballers of all time, Maradona has been battling drug addiction for years.
He was suspended while playing in the Italian championship in the 1990s after testing positive for cocaine.
The Buenos Aires clinic said Maradona was admitted after suffering "congestive heart failure" caused by high blood pressure.
It said Maradona "is receiving medication to strengthen the heart; and as he developed acute respiratory failure he was put on a ventilator and therefore is heavily sedated."
"The reaction to the medication has been favourable, and he is stabilised." But the statement said doctors gave only a "reserved" assessment of his condition.
Cahe told reporters outside the clinic "we will have to wait 24-to-48 hours to know the evolution." He refused to answer questions about whether Maradona had had a drug overdose.
The TN report quoted members of Maradona's "intimate circle" as saying the former footballer was rushed to hospital following an overdose.
Maradona's father, Diego, his ex-wife, Claudia Villafane, and their two children, Dalma and Gianina, had been at the hospital.
Carlos Bilardo, who was coach of the Argentine national football team when it won the 1986 World Cup in Mexico, visited the hospital in the evening but declined to make any statement.
"He wanted to have a few health check-ups," one of the former footballer's close relatives told reporters as rumours mounted that Maradona was in intensive care.