An Aston Villa fan from Norway is causing Premier League managers a lot of grief.
He is behind a bot which tracks players' and staff's fantasy football accounts and it has resulted in real team news being leaked.
It all kicked off when an injury to Aston Villa's Jack Grealish was revealed before their game on Sunday.
Clubs are angry, with Manchester City boss Pep Guardiola calling it "unethical".
But, speaking to BBC Radio 1 Newsbeat, the man behind the bot says he's "sorry, not sorry".
He only goes by his first name, Henning, and runs the Twitter account FPL Insider from Norway which currently has more than 25,000 followers.
It offers followers tips for Fantasy Premier League - an online game where competitors pick their own teams and are awarded points depending on how well the players they choose do in matches in real life.
It all started when he heard that Liverpool's Andy Robertson had transferred teammate Sadio Mane out of his fantasy team at the start of the year.
"I wondered if it was possible to check if Premier League players or staff connected to clubs had made any transfers in the FPL game," he tells Newsbeat.
So Henning says he created the bot - an automated computer programme - that would scan the FPL accounts of staff, players and junior players - who Henning calls insiders. When an insider removes one of their teammates from their fantasy line-up, the bot picks it up and tweets it.
"At the start it was very manual and tedious," he says.
"I had to spend hours on Google, LinkedIn and Football Manager 21 to find staff and even junior players."
From there Henning explains he found individual fantasy football leagues used by multiple footballers and staff.
"It's a lot different between the clubs because some of the clubs have almost official team leagues," he says.
"Wolves have a league where it's basically all the first team players."
Other teams he says were a bit more secretive.
"Everton had funny names that you really had to be clever to find out who they were."
Once he had identified his insiders Henning says he "just had to list it and create some logic in the bot to pick up the transfer activity and connect it to Twitter".
That Grealish tweet
But it blew up when his tweet, confirming that players and staff had transferred Aston Villa's Jack Grealish out of their FPL teams, was retweeted nearly 400 times.
This was ahead of their game against Leicester City on Sunday. Villa went on to lose 2-1.
Leicester's manager Brendan Rodgers admitted he had heard rumours about Grealish's fitness before the game on social media and Aston Villa manager Dean Smith called for an investigation into the leaks from the club.
Manchester City boss Pep Guardiola also raised concerns describing the leaks as "unprofessional and unethical".
Henning says the reaction has been "intense" but he thinks the Grealish tweet "exploded" because Villa "were trying to keep it a secret".
He also says the tweet just confirmed already existing rumours.
"I can understand the frustration," he says, "but this is already available information. I'm just structuring it and packaging it in tweets."
His attitude to the media attention is "sorry, not sorry" but he does regret that the side he supports, Aston Villa, got caught up in this. However he suspects Premier League clubs may already use this information themselves.
"They know that opposition players play fantasy football weekly and I would imagine big clubs all have some kind of analyst that has access to this data already."
As for his own FPL team: "I'm just outside the top 100k, so pretty good actually".