Two Paris St Germain fans were stabbed after leaving the Nou Camp following their team’s Champions League group game against Barcelona on Wednesday.
One supporter was “stabbed with a knife by two suspects in dark clothing and wearing balaclavas”, Spanish police said in a statement on Thursday.
“The victim who was accompanied by other PSG fans was taken to hospital where he remains with an injury to his lungs.”
In a separate attack a fan was stabbed with a knife and taken to hospital but he has since been released.
“Police are working to establish the full facts of what took place and detain those responsible,” the statement added.
It is not known whether the incidents were football related or attempted robbery.
A Deportivo La Coruna fan died following apparently organised fighting near Atletico Madrid’s stadium before a league game on Nov. 30.
Spanish soccer authorities and the government have vowed to banish ultras from stadiums and clamp down on offensive chants.