Before Dortmund's match against Borussia Monchengladbach on Saturday, Jurgen Klopp had an idea. He brought an alarm clock into the dressing-room and let it go off shortly before the match.
he message to his squad was simple enough. It was time to wake up. Perhaps the subsequent 3-1 defeat only confirmed to Klopp that he could no longer rouse his players to the heights of recent years, but it was still another vivid example of his often left-field methods.
Watch footage of Klopp slap and then hug Marian Sarr, a teenage centre-back, as he left the field after a win last season and it is hard not to see something of Brian Clough in a manager whose profile now stands comparison with Pep Guardiola and Jose Mourinho among the heavyweights of the European club game.
That was evident yesterday when news that Klopp would stand down as Dortmund manager reverberated far beyond the Ruhr valley.
The words 'Jurgen Klopp' and the message #dankekloppo were trending not only on Twitter in Germany but across many countries in Europe, including England. Part of that, of course, is out of fascination for what he will do next (sources in Germany are adamant that he is genuine in saying he has not decided) but also because of his personality.
Klopp has charisma and star quality. When he walks into a room, people stop and take notice. He is fun, there is a slight madness about him but he clearly loves life. "Crazy players love me -I don't know why," says Klopp.
He certainly knows how to inspire people.
"Understanding his popularity is easy," explains Lars Wallrodt, the chief football writer of Die Welt. "He has never changed. He is authentic. When you watch him coaching or talking to people, he is always himself. There is no mask, no pretence. He is the sort of guy you would drink beer with."
The irony is that this complete disregard for image has actually created its own brand. The man known as 'Kloppo' is more in demand with companies and sponsors than just about any public figure in Germany.
Whether intended or not, the hoodies, the black-rimmed glasses, the unkempt hair, the booming laugh and permanent five-day stubble have all become hallmarks. Yet there is also vast substance beneath all that.
Twice toppling Bayern Munich for the Bundesliga title and coming so close to winning the 2013 Champions League final tells you that. Such success has been achieved, moreover, while generally selling one or two of his best players every year.
"The important thing is new ideas, not money," he says. "You always want to be the team that can beat the one with more money."
Klopp's football philosophy is clear and compelling but, ask him what really counts, and the response is instructive.
"You cannot win without tactical things but the emotion makes the difference," he says.
There was plenty of that in Dortmund yesterday when news broke of his decision. Dortmund sporting director Michael Zorc actually looked close to tears as he explained how Klopp had "written football history".
Klopp's ability to connect on that emotional level with fans, players and staff was especially striking when he arrived at Wembley just 24 hours before the 2013 Champions League final against Bayern. Having first gone off on a tangent about London traffic and police, he then memorably added: "If this will be the only final in my life, Wembley is the perfect place and the perfect opponent. If I will die in 60 years, it is not so bad.
"We want to look back, when we are old and grey, tell our children and children's children what happened on some days in our life."
Klopp's reputation for attacking football is justified but he is no Guardiola or Arsene Wenger in his outlook.
Possession is not an objective in itself. For him, football is about being direct, attacking, winning the ball as high up the pitch as possible, taking risks and playing at pace.
It is more akin to Manchester United under Alex Ferguson. Klopp once described Arsenal's football as "like a silent song" before adding that he was more of a heavy metal man.
"I always want it loud," he said. "If Barcelona's team of the last four years were the first one that I saw play when I was four years of age, I would have played tennis.
"It is fighting football that I like. Rainy day, heavy pitch, everybody is dirty in the face and they go home and can't play football for the next four weeks."
Like so many of the best managers, Klopp's coaching career has followed an unspectacular playing career.
As a manager, he spent seven years at Mainz, taking them into both the Bundesliga and then Uefa Cup for the first time in their history.
When he then arrived at Dortmund in 2008, he was asked for his ambitions for the club. "To create memories," he said.
Klopp has achieved that aim. He has all the attributes to do the same in England. (© Daily Telegraph, London)