Even with his pleasant, cheerful demeanour, Jurgen Klopp is known to have a fiery temper if any of his players get on the wrong side of him.
He may give out warm, friendly hugs, but behind the scenes Klopp can be a hard taskmaster demanding nothing less than high standards.
And former Liverpool loan star Nuri Sahin was unfortunate enough to find that out when he overstepped the mark during a training session under Klopp's management.
The pair worked together in two spells, with the first from 2008-2011 during Klopp's time as manager of Borussia Dortmund, when Sahin was kicked out of the training session.
“I was playing for Borussia Dortmund and the coach threw me out of training," Sahin told Goal. "He told me to leave, because I had an argument with another player.
“I was young and I thought I knew everything. I was sure I was in the right, 100 per cent, but he told me to go, so I went."
Sahin claims the incident was in 2009 or 2010, when the midfielder would have been just 21 or 22.
He recalled going home concerned his Dortmund career would be over, but was surprised by Klopp's reaction when he came in the next day and the whole issue had been forgotten.
“It was a moment for me to realise that I would have him on my side even when I was in the wrong. It’s powerful when you realise that about your coach.”
Sahin signed for Real Madrid in 2011 and later joined Liverpool on loan under Brendan Rodgers but was taken back to Dortmund by Klopp in 2013.
It's a testament to Klopp's great man-management that problems like that are not a big deal in his eyes and his relationship with his players ensure they do not cloud his judgement.
Klopp recently had another flashpoint with a player, when Sadio Mane refused to shake his hand after the win over Manchester United as the forward was unhappy at being dropped to the bench.
Speaking at the time, Klopp was relaxed about it and said: "Football is an emotional game and everyone expects from us to control our emotions always. It doesn't work out always, that's the case.
"It happened to me as a player, it happened to other players when I was their coach. We had so far no real chance to talk about it but we will and there will be nothing left. Everything will be fine.
"Do you want these things to happen? No, but it's not the first time in my life and I'm afraid to say it won't be the last time.
"The thing is, if somebody shows me respect five million times, and one time not, what is more important?"
Mane has since cleared the air with his manager, with Klopp stating: "“We spoke and he apologised. That's clear and that is it.”
