Diego Maradona remains in an unstable condition in a Buenos Aires hospital with high blood pressure, breathing problems and a lung infection.
But doctors said in a statement on Monday that the 43-year-old was making "satisfactory" progress, and said his arterial pressure was normalising.
Family doctor Alfredo Cahe denied Maradona had taken a cocaine overdose.
Maradona, who has been battling drug addiction for years, is being helped to breathe by a respiratory machine.
The Argentina legend was admitted to the clinic with high blood pressure and respiratory failure just hours after seeing former side Boca Juniors play.
It emerged later on Monday he had also developed a lung infection.
"There has been a slight improvement between last night (Sunday) and Monday morning," said Cahe.
"He is making good progress, but we will be following things closely."
A statement by the Buenos Aires clinic revealed: "Maradona is receiving medication to strengthen the heart.
Fans have been gathering outside the private clinic
"As he has developed acute respiratory failure, he has been put on a ventilator and therefore is heavily sedated."
Since being admitted to hospital on Sunday, Maradona has been visited by family and friends, including his ex-wife and their two children.
Former Argentina coach Carlos Bilardo, his former agent Guillermo Coppola and ex-Argentina international Hector Enrique have also been to see the stricken star.
Cristiana Sinagra, mother of his son Diego junior, said: "We expect him to heal as soon as possible. It's a tough moment but we're confident that he will he get better."
Well-wishers crowded outside the clinic as news of Maradona's plight spread, forcing police officers to cordon off the entrance and hold back the crowd.
One fan held aloft a photograph of Maradona in his playing prime, while a banner read "Diego, Argentina loves you".
In 2000, in Uruguay, Maradona suffered a severe heart attack due to a cocaine
He then began a long recovery treatment in Cuba, but since an overweight Maradona returned to Argentina, speculation and concern has grown over his health.
Our South America correspondent Tim Vickery said
Maradona's general health had been a concern for many years.
"He was continuing to cast his shadow over the Argentine team," he said.
"And what a stumpy shadow it has become. He's put on a lot of weight and when, hopefully, he recovers from this, he really does need to get his weight down.
"He's putting a lot of pressure on a damaged heart."
Maradona enjoyed a colourful 20-year footballing career, moving to Catalan giants Barcelona for £1.7m in 1982 after the World Cup in Spain.
In 1984, he signed for Napoli for a then world record £4.1m and transformed a mediocre club into one of the best in Italy and with whom he won the scudetto.
Now at the peak of his form, Maradona led Argentina to a 3-2 triumph over West Germany in the 1986 World Cup final.
After leading Napoli to the Uefa Cup in 1989, Maradona again played for Argentina in the 1990 World Cup in Italy.
But his displays were generally less effective than in 1986 and, although Argentina reached the final, West Germany's Lothar Matthaus was the star of the tournament and led his country to victory.
In 1991, Maradona failed a dope test for cocaine and was banned for 15 months.
Maradona performed in his fourth World Cup in the United States in 1994 but tested positive for a cocktail of drugs the day before he was due to make a record 22nd appearance in the tournament.
In 2000, Maradona tied with Pele for the accolade of Fifa's best ever player.
He has also been honoured with a musical about the ups and downs of his turbulent rags-to-riches life.
And despite his well-publicised drug problems, Maradona still has a widespread fan club with 20,000 members as far afield as Vietnam and Iceland becoming members of the "Church of Maradona".