Sevilla midfielder Antonio Puerta died on Tuesday, three days after collapsing during a Spanish Primera Liga match against Getafe.
The 22-year-old Spanish international had been in a critical state in the Virgen del Rocio hospital in Seville since being admitted on Saturday. The hospital confirmed his death.
Spanish media said UEFA had agreed to postpone Tuesday's Champions League third round qualifier against AEK Athens and that the team's league match against Osasuna on Monday would also be called off.
An AEK spokesman said the tie will be played on Monday September 3. Puerta collapsed after jogging back towards his own goal 35 minutes into the match against Getafe.
Team mates and medical staff rushed to his side and were seen preventing him from swallowing his tongue as he lost consciousness.
He was able to walk from the pitch but doctors said that he collapsed again in the changing rooms and had to be given cardiac resuscitation before being taken to hospital.