
The fan was treated by medics at the stadium before the game, which delayed the kick-off by a few minutes, and then taken to the hospital.
“We profoundly regret the sad news of the death of the Valencia fan who was urgently treated tonight at Mestalla before the start of the game,” said Valencia on Twitter late Friday.
“A lot of strength and an enormous hug to his family and friends. RIP.”
Cadiz players appeared to alert medical services to the incident – a heart attack according to Spanish media – which occurred while the teams were warming up.
The Andalusian side won thanks to Ruben Alcaraz’s early goal to climb provisionally to 17th.