Iker Casillas was "not aware" he had a heart attack until after his operation, his agent has confirmed.
Porto confirmed goalkeeper Casillas had suffered an "acute" heart attack during training on Wednesday, but that he was stable in hospital and "the heart problem has been resolved".
The Spanish World Cup winner later tweeted: "Everything under control here, it was a big scare but I'm feeling strong. Thanks a lot for all your messages and your support."
Agent Carlos Cutropia described the 37-year-old's recovery as his "greatest victory" although he had little awareness of the severity of the situation until afterwards.
“He was not aware of what was happening to him, of having a heart attack," Cutropia told Spanish radio station COPE.
“At no point did he faint or lose consciousness. He felt unwell but he didn’t think he had suffered a heart attack, he was only told after his operation.
“Then he was happy because he was well and what he suffered has not left him with any consequences.
“He has never had any symptoms. It is something that is not usual, especially in an athlete, and this has been a surprise for everyone.
“He had all the luck in the world. If this comes to you at home, the consequences would have been tremendous.”
Casillas had been preparing for Porto’s league game with Aves this weekend, although he is now unlikely to play again this season.
“Iker was halfway through the training when his chest, his mouth, his arms hurt a lot," he added.
“Quickly the medical team from Porto, to whom we thank for their professionalism, took him to the hospital.
“He has already begun to recover. In the afternoon I was already making jokes and it was the normal Iker.”
