Sevilla captain Andres Palop has spoken of the shock in the dressing room after team-mate Sergio Sanchez was found to have a heart condition.
Sanchez has now travelled to Barcelona to be with his family - missing Saturday's game against Atletico Madrid - and will not be considered for selection until the problem has been thoroughly examined.
The 23-year-old joined Sevilla from Espanyol last July, and has been competing with Abdoulay Konko for the right-back slot.
Palop said: "The dressing room is concerned, we were not expecting news like that.
"The important thing is his life, they've taken these measures for his own good.
"We hope that the specialists help him to remain active. The good thing is that it was detected in time."
Spanish players called for improvements in screening procedures for heart problems following the death of Espanyol defender Dani Jarque in August, two years after Sevilla midfielder Antonio Puerta collapsed during a game and later died after a prolonged cardiac arrest.
Sevilla coach Manolo Jimenez hoped Sanchez's condition was only a scare.
He added: "Imagine (how we feel) considering what we have been through here.
"With the precedents that there are it's wise to be cautious and you have to congratulate the doctors and cardiologists who examined him."
Club president Jose Maria del Nido said Sevilla may tap this month's transfer market if needed.
He said: "He's a young kid, with a splendid future and a meteoric career and the fact he has had this setback now is a blow.
"It implies that we will reconsider the player's situation and confirm whether his absence is definitive.
"In that case, we would also consider strengthening that position."