Porto goalkeeper Casillas suffers heart attack but is in stable condition

Spain's World Cup winning captain Iker Casillas suffered a heart attack while training with Portuguese club Porto on Wednesday, but later tweeted from hospital to say he was back to full strength.

Casillas, 37, played 167 times for Spain and famously captained them to their first ever World Cup win in 2010.

He also won the 2008 and 2012 European Championships with the national side and his exploits earned him the nickname "Saint Iker" as well as making him one of Spain's best-known personalities.

Porto said Casillas had suffered an "acute" heart attack during training, but that he was stable in hospital and "the heart problem has been resolved."

Casillas later tweeted: "All good here, a great scare but have all my strength. Many thanks to all for the messages and affection."

Casillas' biggest victory is surviving the heart attack, his agent Carlo Cutropia has said.

"This is more important than winning the World Cup," Cutropia told Radio Marca. "This is the biggest victory of his life. Iker has made the best save of his life.

"He had a sharp pain in his chest, mouth and arms during training. He wasn't aware he was having a heart attack. He never had any symptoms. he has had all the luck in the world that this happened during training and in front of FC Porto's medical team. Had it happened at home, the consequences could have been unpredictable."

Casillas started his career with Real Madrid, where he spent 16 seasons and won the Champions League on three occasions as well as La Liga on five occasions before joining Porto in 2016.

Born in Mostoles, Madrid, Casillas' 725 matches between 1999 and 2015 put him behind only his former teammate Raul, with 741, on Real's all-time list.

The goalkeeper is married to the Spanish television journalist Sara Carbonero, with whom he has two children.

Upon hearing news of the heart attack, former club Real Madrid released a statement on Casillas' behalf, as did Real's eternal rivals Barcelona, the Portuguese League, and Spain's La Liga among others.

"Real Madrid C. F. wishes to offer its full support to our beloved captain Iker Casillas," the Real Madrid statement read. "Iker Casillas has shown us how to overcome the most incredible challenges throughout his professional career, adding significantly to our club's successes.

"He's shown us that giving up has no place in our way of life and demonstrated time and again that staying strong during the hardest of challenges is the only path to victory.

"Real Madrid C. F. and all of madridismo look forward to seeing our legendary captain back in good health as soon as possible and we send him all the encouragement in the world."

Reuters contributed to this report.