A mass brawl before Rangers' Europa League match in Glasgow clash left two men in the hospital with stab wounds, police said.
Rangers fans clashed with their counterparts for Croatian side Osijek a short distance from the Ibrox Stadium in what Police Scotland called a "large-scale disturbance."
Two men, aged 24 and 40, were taken to Queen Elizabeth University Hospital for treatment and were in stable condition on Thursday night.
"This type of violent behaviour will not be tolerated and it is absolutely vital anyone with information that could assist with our investigation comes forward," Detective Inspector Steven Wallace told British media.
"I would appeal to anyone who was in the area and witnessed a disturbance, particularly anyone with mobile phone or dash-cam footage, to get in touch."
The clubs played to a 1-1 draw in the second leg of the second qualifying round, with Rangers advancing 2-1 on aggregate.