Atletico Madrid have condemned the fighting between supporters that left one man in a serious condition and several others with minor injuries before Sunday's match against Deportivo La Coruna.
Trouble flared in the Madrid Rio public park, close to Atletico's Vicente Calderon stadium, ahead of a match that began at midday local time (1100GMT).
According to reports in Spain, groups of Atletico and Deportivo hooligans gathered at the site where the violence began at around 9am.
Two supporters were attacked and thrown into the Manzanares river, the newspaper El Pais said on its website, with the most worrying situation concerning one of the two men - said to be a 43-year-old Deportivo fan - who was reported to have suffered a cardiac arrest. There were also reported to have been stab injuries.
Spanish league authorities had wanted the match to be postponed but said it was not possible.
The Liga de Futbol Profesional announced on its website: "The LFP expresses its condemnation at the incidents that took place on Sunday morning on the outskirts of the Vicente Calderon stadium before the week 13 match in La Liga between Atletico Madrid and Deportivo La Coruna.
"The LFP has been steadfast in its intention to suspend the match and it has not been possible. The association is working with Fans United, the national police and all clubs and societies to end violence, racism, xenophobia and intolerance in professional football."
Atletico Madrid issued their own statement, saying: "Atletico Madrid strongly condemns the incidents in the area of Madrid Rio in the hours before the match against Deportivo La Coruna.
"The values that promotes sport should prevail over any rivalry and together we must fight against the scourge of violence."
