Bayern Munich stars Robert Lewandowski, Manuel Neuer and Serge Gnabry were recently named in a worrying death threat that called for them to be shot.
The alarming letter was sent last month and described the trio as "dirty Bavarian pigs."
The note was delivered to second tier outfit St Pauli - not Bayern's Allianz Arena.
St Pauli are based in Hamburg, which is located around 430 miles north of Munich. It would take around eight hours to drive between the two German cities.
Police in Hamburg are currently examining the note for fingerprints and DNA traces. Bayern and the German FA are said to be waiting for the outcome of the investigation.
Who will win the Bundesliga this season? Let us know in the comments below!
"Save the league, save football," the letter read, as quoted by German newspaper Bild. " Fire and death to the dirty Bavarian pigs."
The concerning note named Lewandowski, Neuer and Gnabry and also made threats to Bundesliga referees.
The German State Criminal Police Office (LKA) are currently trying to identify whether more letters have been sent to other clubs.
"We are investigating on suspicion of threatening and disturbing the public peace by threatening to commit crimes," said a police spokesperson.
"We will check the backgrounds."
Bayern are currently six points ahead of Borussia Dortmund at the top of the Bundesliga and have a great chance of winning a 10th successive title.
The Bavarian giants have won 31 German championships in total, 30 of which have come since the Bundesliga was formed in 1963.
Bayern have also enjoyed success in the DFB-Pokal - the German Cup - winning five of the last nine tournaments.
Bundesliga chiefs are reportedly considering implementing a new play-off format - similar to the one used in American sports - to give other teams a chance of winning the title.
"There are no taboos for me," new German Football League CEO Donata Hopfen told Bild earlier this month. "If play-offs will help us, then we'll talk about play-offs."
Some European countries have adopted a similar idea. The Austrian Bundesliga has a "championship round", which sees the top six teams battle it out for the title.
Top-flight leagues in Belgium, Czech Republic, Denmark and Scotland have implemented similar models, although none of them have play-offs.
The play-off model does hamper the importance of the regular season.
In the MLS, 2021 champions New York City finished eighth in the regular season - 22 points behind table toppers and Supporters' Shield winners New England Revolution.
Bayern have surprisingly welcomed the idea, despite it threatening their dominance.
"A format with semi-finals and a final would mean more excitement for the fans, so it makes sense to explore these ideas," the club's CEO Oliver Khan told Kicker magazine.
"We're always open to new suggestions."
Dortmund's CEO Hans-Joachim Watzke added: "I have never been a fan of play-offs, but given the current situation, we can't afford to have any fundamental red lines."
