The 82-year-old was admitted to hospital in Sao Paulo on Tuesday, saying it was a routine monthly visit. However a report in Brazil, which has not been confirmed, says he is now beginning end-of-life care after not responding to chemotherapy.
“Pray for the King,” France forward Kylian Mbappe tweeted.
The three-time World Cup winner had a tumour removed from his colon in September 2021 and has since had regular treatment.
Pele was diagnosed with a respiratory infection and on Friday Sao Paulo’s Hospital Albert Einstein said he was in a stable condition.
Speaking on Saturday, England captain Harry Kane said: “We are very sad to hear news of him being ill but we wish him well, not just me but the whole England set-up. He’s an inspiration, an incredible person.”
World Cup-winning former Germany forward Jurgen Klinsmann, speaking on BBC One’s World Cup coverage on Saturday, added: “Pele is just such a wonderful person. The outstanding personality of world football. We can just pray and hope for the best but it’s very sad news.”
The Lusail Stadium in Doha, which will host the World Cup final on 18 December, and the Aspire Tower next to the Khalifa Stadium, were adorned with pictures of Pele in his famous number 10 shirt.
Concerns were initially raised on Wednesday when ESPN Brasil reported Pele had been admitted, with his daughter Kely Nascimento saying there was “no emergency” involved.
Pele thanked well-wishers on Friday for sending “good vibes” and said his stay in hospital was “a routine visit”.
The former striker is Brazil’s all-time leading scorer with 77 goals in 92 games and scored in four World Cup tournaments.
Santos, his only Brazilian club, tweeted: “It’s the whole world wishing you well, King Pele”.