Former Brazil captain Socrates has died at the age of 57.
He had been in a critical condition with an intestinal infection since being admitted to intensive care on Friday at a hospital in Sao Paulo.
Socrates, who was widely regarded as one of the greatest ever midfielders, was moved onto a life support machine on Saturday.
He played in two World Cups, won 60 caps for his country between 1979 and 1986 and scored 22 goals.
The former Corinthians player, whose full name was Socrates Brasileiro Sampaio de Sousa Vieira de Oliveira, was taken to the Albert Einstein Hospital in Sao Paulo with food poisoning on Friday, according to his wife.
A hospital statement said on Saturday that the former footballer was "in a critical condition due to a septic shock of intestinal origin".
It added he was breathing with a ventilator and using a dialysis machine.
Socrates was taken to hospital twice in August and September this year with bleeding in his digestive tract.
After these incidents he admitted he had problems with alcohol, especially so during his playing career. He is also well known for his smoking habit.
In a recent television interview, Socrates said he had considered alcohol his "companion" but believed its regular use did not affect his performance on the field.
"Alcohol did not affect my career, in part because I never had the physical build to play this game," he said.
"Soccer became my profession only when I was already 24. I was too thin and when I was young I did not have the opportunity to prepare myself physically for the sport."
Socrates so much more than a footballer by Tim Vickery
Just over five years ago, when Brazil's 1982 World Cup coach Tele Santana died, team captain Socrates recalled the scene in the dressing room after their elimination by Paolo Rossi's Italy at the second group stage.
As the media were searching for explanations, there were tears and tantrums, dejection and disappointment. Amid the chaos, Santana stood peacefully, proud of his team and the glorious football they had played - still remembered with extraordinary affection all over the world. They had given it their best shot.
True, the campaign could have gone on for longer but what memories they left behind. That same philosophy could serve as the epitaph of the captain.
Losing Socrates at the age of 57 seems ludicrously premature. His death hits hard because this is much more than the passing away of a great player. Socrates was an extraordinary talent.
His synthesis of intelligence and technical brilliance are nowhere better illustrated than in his mastery of the backheel - a resource which gave him an advantage over more physically gifted opponents.
But he was by no means the greatest. Zico, Falcao and Cerezo, his team-mates in Brazil's wonderful 1982 midfield, all have claims to be considered better players - an indication of just how exceptional that side really was.
Socrates may have been best known internationally for his World Cup exploits, especially those of 1982 but, at home, his name is intrinsically linked with his early 1980s spell with Corinthians of Sao Paulo. And his importance went well beyond the football field.
At the time Brazil was ruled by a military dictatorship. The regime had a cynical slogan aimed at silencing dissent: "Brazil - love it or leave it".
Socrates had an alternative - change it. He was the leading light in a movement at the club which became known as "Corinthians Democracy". Players, coaching staff and club employees would vote on all kinds of issues of interest to the collective - from which players to sign, to whether the team bus should stop to allow people to get off and relieve themselves.
This was successful in football terms, transforming a struggling team into a cohesive, victorious unit. Corinthians won the Sao Paulo State Championship in 1982 and 83, a time when the title still meant something.
More than that though, the movement served an educational purpose for millions - imparting the value and virtues of democracy at a time when they were seen as dangerously subversive.
It was an embryo of a future, better Brazil. This is why Brazil's president Dilma Rousseff, herself a victim of the military government, referred to Socrates as "a champion of citizenship" on Sunday.
He was a voice taken from us when he still had so many things to think and to say.
He was, for example, concerned about Brazil's preparations to stage the 2014 World Cup.
Just over a month ago, he said: "[It has been] very badly organised. There is an inversion of values. The way it's being done, it would be better for Brazil not to have the World Cup. It is a private product that is using public resources."
One can agree or disagree. But his was a contribution to the debate that needed to be heard. Certainly it is to be hoped that Ronaldo took note.
The former striker, now 35, last week joined the board of the 2014 Local Organising Committee, where he clearly runs the risk of being used as a shield by the bungling power structure of the Brazilian game.
The signs are not promising. In his debut press conference Ronaldo let slip that "you don't make a World Cup with hospitals" - a comment guaranteed to irritate a trained doctor such as Socrates.
In 2003, Fifa announced South America would host the 2014 World Cup as part of their policy to rotate the tournament around continents. A year later, the South American Football Confederation voted to hand the tournament to Brazil.
But the absence of a competitive bidding stage removed discipline from the process. and, as a result of all the delays, an emergency has been artificially created.
The only solution is to throw money at the problems which have been allowed to accumulate.
The power structure will attempt to silence its critics by playing the nationalist card. Anyone not happy with the 2014 World Cup will be guilty of a lack of patriotism.
But there is no way they would have been able to slip that one past Socrates - whose very name included the word in Portuguese for "Brazilian".
A few hours after Socrates Brasileiro Sampaio de Souza Vieira de Oliveira died, Corinthians became champions of Brazil, winning the 2011 championship by a two-point margin from Vasco da Gama.
Did it happen as a homage to Socrates? Maybe. But Sunday's title-clincher was a 0-0 draw with local rivals Palmeiras, an ugly game in which four were sent off. Socrates would surely have wanted something more aesthetically pleasing.
His 57 years with us paid witness to the view that football and life are not just about what you do - the way you do it is at least as important.
Socrates did it in a way that can make football fans proud that he was one of us.