According to Portuguese outlet O Jogo, the Porto goalkeeper is expected to announce his decision on Friday after suffering from a heart attack while training with the Portuguese club. The 37-year-old is one of the most successful Spanish football players of all time, having led his country to the 2010 World Cup win, as well as back-to-back European Championships in 2008 and 2012. His exploits for the national team earned him the nickname 'Saint Iker' and made him one of the best known personalities in Spain. The legendary goalkeeper born in Mostoles, Madrid, and burst onto the scene when he made his debut for boyhood club Real as a teenager in 1999, having come through the club's ranks. During his 16-year run at Real Madrid, Casillas won La Liga five times besides lifting the Uefa Champions League trophy on three occasions, in 2000, 2002 and 2014. He also helped win two Copa del Rey titles, two Uefa Super Cups, one Intercontinental Cup and the Fifa World Club Cup. He joined FC Porto in 2015 and recently extended his contract to 2020 with the option of an additional 12 months. He said Porto had told him they wanted to keep him until he turned 40.