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Working for Jurgen Klopp is an intense experience but one of his former colleagues insists that even when he went “crazy”, the now Liverpool manager was “a special guy” because he would admit to overstepping the mark.

The Reds boss is well-known for driving his teams hard in the pursuit of success – how else could he follow-up a Champions League win with a 25-point lead in the Premier League over the title winners of the past two seasons – but his former Borussia Dortmund physio believes part of the 52-year-old's greatness is that he will always acknowledge his mistakes.

Like Klopp, long-serving medical man Frank Zollner is a legendary figure at the Ruhr club having served them between 1992-2009, a period in which they won a hat-trick of Bundesliga titles plus a first-ever Champions League.

Now working for German second division outfit Bochum, Zollner acknowledges there was seldom a dull moment when part of Klopp's backroom staff.

He told Goal: “He's a special guy.

“There were so many days when you'd think: 'Great guy!', but sometimes you'd think: 'What an egocentric!'

“One time, Jakub Blaszczykowski called me when he was coming back from the [Polish] national team.

(Image: PATRIK STOLLARZ/AFP/Getty Images)

"He said he couldn't train because of a muscle injury but would still come to the team meeting.

“Before the meeting, I went to Klopp with Kuba (Blaszczykowski) and told him what was going on. He then went pretty crazy, probably because he had only just learned about Kuba's injury at that moment.

“Zeljko Buvac (Klopp's former assistant) would often appear at such moments and say: 'Kloppo, smoke a cigarette now and calm down!'

“He was one of the best assistant coaches I've ever worked under.

"But Kloppo had the balls to apologise when the way he treated someone was too much.”