Brazilian World Cup winner Cafu is mourning the death of his son, Danilo.
The Albert Einstein Hospital in Sao Paulo confirmed to Omnisport the passing of the former defender's eldest child.
No further information was provided in line with a request from the family.
Cafu's former clubs including Sao Paulo, Roma and AC Milan have expressed their sympathies.
On Twitter, Milan said: "Our Cafu has lost his son, Danilo. It's with a sad heart that we offer our deepest condolences to his family at this saddest of times."
Cafu's former team-mate at Roma, Francesco Totti, added: "I've seen him grow... it's not possible!!!! Rest in peace Danilo."
Cafu, 49, retired from playing in 2008 and has since held various ambassadorial roles. He won the World Cup with Brazil in 1994 and 2002.