Labeled as "sporadic disorder" by British police and "jovial" by others, Arsenal's Europa League match against Cologne on Thursday divided opinion of those in the stands and watching on television.
Despite only being given 3,000 official tickets, thousands of other Cologne fans flocked to London in celebration of the club's first appearance in European competition for a quarter of a century.
Earlier on Thursday it became clear this was going to be no ordinary European football game as thousands of chanting Cologne fans marched through central London.
Later some quick-witted Cologne fans even bought themselves Arsenal scarves and changed the backgrounds on their phones to the Gunners' club crest to gain entry using home tickets.
"There were also a number of incidents resulting from sporadic disorder inside the ground after away fans gained access to seating assigned to Arsenal supporters," said the Metropolitan Police in a statement.
"As a result of these actions, kickoff was delayed for almost an hour.
"Additional officers and police dog units were deployed to the area to respond to the disorder. Three officers were injured as a result of the disorder, none of them seriously, and five people were arrested on suspicion of public order offenses."
However, home and away fans also mixed peacefully in the stands and on the concourse, exchanging renditions of their favorite club songs at Thursday's match.
"Loudest away support I've ever seen at a game in England," said leading footballer writer Michael Cox on his Instagram account.
In opening disciplinary proceedings, European football's governing body's investigation will look at disturbances, setting off fireworks, throwing of objects, acts of damage and blocked stairways.
"This will be dealt with by the UEFA Control, Ethics and Disciplinary Body on September 21," a UEFA statement read.
A number of media commentators argued that the Cologne fans had given English supporters a glimpse of what's been lost in an age where clubs are heavily reliant on television deals and less so on paying spectators.
"There was undoubtedly something gripping about the spectacle of the Emirates being overrun by a more vibrant, angrier, passionately involved footballing culture," said the Guardian's Barney Ronay.
In Germany, fans of rival clubs are accustomed to sitting together in certain sections of their stadiums, a tradition that no longer exists in Britain.
As journalist Tony Evans suggests, an argument can be made for the change in fans' behavior towards their opposition when a large, metal fence is erected between them.
Once the game got going, Arsenal's Emirates Stadium, popularly known among English fans for its often tame atmosphere, rocked to deafening noise and shaking stands, as Cologne fans jumped in unison with their backs turned to the pitch.
Perhaps this video, taken by a Cologne fan in the Arsenal home end, best sums up the relationship between the fans on the night.
"I can't wait for Cologne away now!" wrote one excited Arsenal fan on Twitter.
Arsenal won the game 3-1 after Cologne had lead at halftime.