The build-up to Barcelona's Liga visit to Alaves was marred by violent clashes between the two clubs' fans ahead of kick-off on Saturday.
Police sources in Vitoria confirmed to Goal that factions of each sides' ultra groups were behind the incidents.
In a video taken in the Basque city, hooded assailants can be seen throwing chairs and attacking rivals with clubs before the game.
One individual was sent to hospital due to the injuries sustained in the battle, while police affirmed that so far there had not been any arrests made in connection with the events.
While the violent episodes were confined to a tiny fraction of the supporters, they raise concerns over the coming Copa del Rey final, which is yet to have a confirmed venue.
Barcelona and Alaves will meet again in the showpiece match, after the Catalans downed Atletico and Celta were beaten by the Vitoria club in the last four.