Arsenal tweeted: “The kick-off of #AFCvCOL has been delayed by an hour in the interests of crowd safety.”
Over 20,000 Cologne fans are understood to be in London for the match despite their ticket allocation being 2,900.
Video footage showed thousands of German supporters singing through the streets of London throughout the afternoon.
But the number of fans around the Emirates stadium has meant the game has been delayed by at least an hour due to crowd safety.
There are unconfirmed reports that some Cologne fans have attempted to storm their way into the stadium.
vCard.red is a free platform for creating a mobile-friendly digital business cards. You can easily create a vCard and generate a QR code for it, allowing others to scan and save your contact details instantly.
The platform allows you to display contact information, social media links, services, and products all in one shareable link. Optional features include appointment scheduling, WhatsApp-based storefronts, media galleries, and custom design options.
They have reportedly purchased home tickets from touts and attempted to move into the away end, causing riot police to intervene.
Cologne are playing in Europe for the first time in 25 years.
Once the game gets underway, it will be a much changed Arsenal team.
Arsene Wenger has made nine changes with Alexis Sanchez starting for the Gunners, while Jack Wilshere is named on the bench.