German football fans have been holding silent protests during games over plans to reduce standing in stadiums.
The controversial security proposals by the German Football League (DFL) would also see away fans' ticket allocations for Bundesliga matches slashed in half.
Supporters' groups have reacted angrily to the 'Safe Stadium Experience' paper and Tuesday saw the first wave of protests, with fans urged to stay quiet for the first 12 minutes and 12 seconds of each game.
The time is a reference to 12 December, when Bundesliga clubs will vote on the proposals.
Most fans observed the silence, with Philipp Markhardt, spokesman for the ProFan group, explaining: "The protest is to show the clubs what it would be like if we were not there."
Borussia Dortmund captain Sebastian Kehl said it was a "funny feeling" playing in front of silent stands in the game with Fortuna Duesseldorf in front of 80,100 people at Signal Iduna Park.
He added: "They (the fans) want to use the symbolic time of 12:12 to send a clear sign.
"It wasn't just our fans, but many more in the Bundesliga. It is a symbol towards the DFL paper."
Germany's top 36 clubs will vote whether to accept the proposals, which also include the introduction of body searches, at next month's meeting.