Basque police did not hesitate to get rough with Apoel fans after a fresh wave of violence on Thursday night, just before the match with Bilbao, which the team dressed in orange later lost.
According to Spanish daily Marca, local police officers were embedded with the group of hard core Apoel fans on their way to the stadium.
At one point, there were altercations and objects thrown between Cypriot and local fans, with officers trying to put order.
The Basque police later decided to get involved by taking part and even hitting back when officers came under threat or if they were provoked, according to reports.
Two fans and one officer sustained light injuries, while three Apoel fans were arrested. Two of them were let go the same evening, while the third suspect was released Friday morning.
All three were ordered to appear in court at a later date to give new statements.
APOEL gave themselves a fighting chance to make history by knocking out Athletic Club and reach the Last 16 of the Europa League after a 3-2 defeat in Bilbao.
But the match was marred with pre-game violence even a day earlier, when dozens of APOEL and Athletic Club fans kept Spanish police on their toes on Wednesday night.
During those previous altercations, some fans of the Cypriot champions received medical assistance and others were arrested.