Porto are "extremely united" behind Iker Casillas following his heart attack, the team's head coach Sergio Conceicao has said.
Former Real Madrid and Spain goalkeeper Casillas took ill in training on Wednesday, and had to be transferred to hospital.
It was later confirmed that the 37-year-old had suffered a myocardial infarction, though he is in a stable condition and on course to make a recovery.
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At a news conference ahead of their game with Desportivo Aves, Conceicao spoke of his players' shock when they were informed of the seriousness of Casillas' problem.