Unsavoury scenes have erupted between West Ham and AZ Alkmaar fans ahead of the second leg of tonight's Europa Conference League semi-final.
The Hammers took the advantage in their first tie but made it hard for themselves, coming from behind to defeat the Eredivise side 2-1 at the London Stadium last Thursday.
Concerns have already been raised by the FA and the Met Police over the safety of fans heading to the final on June 7, should West Ham progress.
But tonight's meeting has been marred by what is being described by Dutch news outlet NH as a 'grim atmosphere' as riots between hooded figures have broken out today on the streets of Alkmaar.