NFL fans in London were forced to battle through enormous queues and face severe delays following an issue with their OnePass ticketing app at the Tottenham Hotspur Stadium on Sunday afternoon.
The American powerhouse sport has made the north London stadium its home in the UK, hosting a number of games at the ground throughout the season.
Kicking off the run of ties in London is a meeting between the Cleveland Browns and the Minnesota Vikings.
Sunday marks the first time that the two sides have faced one another in capital in nearly 10 years, with their last meeting coming in 2017 at Twickenham.
But fans looking to soak up the atmosphere inside the ground were instead let down amid reported problems with the apps needed to store tickets for the game.
Videos and pictures from outside the Tottenham Hotspur Stadium showed the approach clogged up with fans not moving as they sought to find a way in before kick-off.
The NFL returns to London with two highly anticipated clashes scheduled for October
But fans' experience of Cleveland Browns vs Minnesota Vikings was mired by tech faults
There were also queues at the box office as supporters looked to get to the bottom of the chaos.
'The NFL ticket app gone down - Thousands stranded outside Tottenham Hotspur’s absolute shambles….' one user noted.
'Very disappointing service…. Hope to see the Cleveland #Browns play at some point - hopefully we get a refund from (the NFL) of everything we missed.'
Another captioned a video of trailing queues: 'Hey (Ticketmaster) and (the NFL) your one app sucks. No one can get into the game. Here’s the line at the box office.'
'Absolute s***show today at NFL London,' a third wrote. 'OnePass app is not working for thousands of fans and are in a massive Queue for ticket office.
'Will 100% miss kickoff. Disgraceful.'
'Hey (NFL) waiting in line for over an hour for help because your app is crap,' another continued.
Fans shared pictures of the OnePass app appearing not to recognise the tickets in question
Spurs will go on to host the New York Jets against the Denver Broncos in one week's time
Pictures of the app's malfunction were also widely shared on social media, with some showing that not only the OnePass app, but Ticketmaster itself were also failing to display for users.
Amid the disappointment, NFL London urged fans to check at the gates with their confirmation email, rather than the pass on the app itself, in a bid to reduce delays.
American football will return to the ground the following Sunday, for a clash between New York Jets and Denver Broncos.