Rayo Vallecano are reportedly not selling their season tickets online which has forced fans to stand in long queues to collect their tickets in scorching heat.
One such fan fell ill in the ticket queue and an ambulance had to be called for the person.
It is believed the supporter collapsed due to heat exhaustion.
Rayo are off to a great start in La Liga this season winning back-to-back games against Almeria and Granada.
The club play their first home game of the season on August 28 when they host Atletico Madrid.