Porto keeper Iker Casillas has been rushed to hospital after suffering a heart attack at training.
The World Cup-winning Spanish stopper is reportedly "out of danger" after receiving treatment on Wednesday morning.
Casillas, a Real Madrid legend, now plies his trade in the Portuguese top-flight and is one of the most decorated footballers of modern times.
But he took ill at Porto training and Portuguese media report he was immediately taken for surgery.
The 37-year-old is now believed to be in a stable condition following the incident.
"Iker Casillas suffered an acute heart attack during this Wednesday's training session," Porto said in a statement on their official website.
"The session was quickly halted so medical assistance could be provided to the Porto goalkeeper, who is currently in the CUF Porto Hospital. Casillas is ok, stable and the heart problem has been resolved."
Casillas was Madrid's No.1 for 16 years after making his debut as a teenager in 1999.
He won the Champions League three times, La Liga five times and the Copa Del Rey twice during a glittering career with Los Blancos.
The stopper was also key to the dominant Spain side that won three major tournaments on the spin and is the country's record appearance holder with 167 caps.
He was between the sticks for their successes at Euro 2008, World Cup 2010 and Euro 2012.
