Borussia Dortmund CEO Hans-Joachim Watzke has admitted his club underestimated ticket demands for their Champions League home semi-final against Real Madrid after fights broke out on Tuesday.
Dortmund host Real at Signal Iduna Park stadium on April 24, but there was chaos before tickets went on sale at 0900 (0700 GMT) on Tuesday, half an hour later than planned, as brawls broke out between fans, many of whom had queued overnight.
Around 100 police officers were deployed to break up scuffles amongst supporters waiting in queues at separate locations in Dortmund city centre as the tickets available were snapped up within an hour.
"We had honestly underestimated this incredible stampede, it's our fault" admitted Watzke after some fans had queued since Sunday evening.
"We will learn our lessons from this and not offer a free-for-all ticket sale in future."
Police had organised the lines from midnight Monday after gangs had tried to aggressively jump in, but officers reported fights breaking out in the early hours of Tuesday morning.
Two people were arrested and charged with assault, while a third was taken into custody and paramedics had to twice intervene after fans collapsed in the lines.
Watzke said Dortmund will reorganise their advance ticket sales in future so organised gangs, operating on the black market, can not profit and to avoid the chaos that left some fans empty-handed despite queuing overnight.
After some supporters began camping out 36 hours before tickets went on sale, Dortmund president Reinhard Rauball and club icon Norbert Dickel had handed out hot dogs and drinks to the queuing masses.
While things remained relatively calm outside the main office at the Dortmund stadium, things turned ugly at other ticketing offices in the city centre.
Local police are critical of Dortmund's planning and a spokesman said: "Since there was no security at a few ticket agencies, officers from Dortmund police had to intervene."