When Arsenal met FC Koln in the Europa League precious few could have predicted the fireworks that would ensue.
First of all, the Bundesliga side brought over around 20,000 fans to the English capital and proceeded to march through London.
The Gunners had allocated them 2,900 seats, but around 17,000 of the Koln supporters made it into the ground with home tickets to make it a unique atmosphere indeed.
To make matters worse for Arsene Wenger's men, Koln took the lead early in the first half when Colombian Jhon Cordoba capitalised on compatriot David Ospina's mistake.
Arsenal went in at half-time 1-0 down and had to turn it up a gear in the second half to grind out the result they needed.
They did just that with three second half goals to end up comfortable winners. Sead Kolisinac got the ball rolling with a thunderous left-foot volley before Alexis Sanchez curled in a world-class effort and Hector Bellerin completed the rout from close range.
Jack Wilshere even made his comeback from injury and a loan spell with Bournemouth in the fixture and played a smart part in the third and final goal.
One man that can understand both sets of supporters is Lukas Podolski.
The 130-time German international had two spells with Koln before moving to Arsenal in 2012 and was a big hit with the fans at both clubs.
As you can see from his tweet above, he thoroughly enjoyed the Koln fans making their presence felt at the Emirates Stadium.
However, plenty of fans did not appreciate Podolski's take and felt he ignored the violence that had taken place.
Wenger said after the game about the Cologne fans: "They were very clever. I don't know how they were able to infiltrate into our fans but they did it very well."
Arsenal now have a date with Chelsea on Sunday at Stamford Bridge where Alexis Sanchez will surely come back into the fold.
Should the Gunners suffer another early season defeat, the pressure will mount on the manager.