Wolverhampton Wanderers fans were attacked by a group of Standard Liege hooligans in the Portuguese city of Porto on Tuesday night.
The attack took place outside the Adega Sports Bar on Jose Falcao street.
The Belgians also tried to get into the bar, smashing windows in the process, but failed.
One man were taken to hospital after the confrontation, according to reports.
The English side are in Portugal to face Braga, while Standard Liege are also there as they play Vitoria, both in the Europa League on Thursday.
Wolves and Standard Liege fans clashed in Filipa de Lencastre Square in Porto on Wednesday.
There were no arrests made.