Zico led the tributes to Socrates after the former Brazil captain died at the age of 57.
The midfield great was being treated for food poisoning at the Albert Einstein Hospital in Sao Paulo but, owing to his already ill-health - it was his third hospital admission of the year - he was unable to recover. Speaking after his initial hospitalisation in August, Socrates had revealed his poor condition was the result of alcohol abuse.
He died of severe septicaemia and was buried in the town of Ribeirao Preto on Sunday, with large crowds turning out to pay their respects. Zico, who played with Socrates for Brazil over many years and briefly for Flamengo, said of his friend: "He was an amazing guy. As a player what is there to say, he was one of the best who ever played."
Zico told globoesporte.com: "A high quality he possessed was loyalty. I had the privilege of being his friend. Our children are friends. He's going very early. He had unusual intelligence. You always expected something good from him."
A statement on the Brazilian Federation's website said: "President Ricardo Teixeira, on behalf of the directors and staff of CBF, expressed sorrow over the death of Socrates, the captain of the Brazilian team in the 1982 World Cup."
A cultured midfielder, Socrates won 60 caps for Brazil, scoring 22 goals. As well as the 1982 tournament, he also played at the 1986 World Cup in Mexico but never managed to win football's biggest prize.
Politically active and influential beyond football in his playing days and a qualified doctor - he took his exams while playing - Socrates was named in World Soccer's top 100 players of all-time and was put up as one of compatriot Pele's 125 greatest-ever players.
His brother Rai was a World Cup winner with Brazil in 1994 and said of Socrates on Sunday: "Everyone knows the story, his importance not only for football but for the country."
Socrates' club career included spells at Botafogo, Corinthians, Fiorentina, Flamengo and Santos, while in 2004 he make a one-off appearance in England, as substitute in a match for lower-league side Garforth Town.
A minute's silence was held in his honour before every match in the final round of the Campeonato Brasileiro on Sunday. Socrates' former club Corinthians gained a goalless draw from their season finale against Palmeiras to win the Campeonato title.