​Borussia Dortmund attacking midfielder Mario Gotze has claimed that his ex-boss and current ​Liverpool manager had an unknown, very serious side to himself. ​

Now 26, the German World Cup winner won two ​Bundesliga titles working under Klopp at Dortmund, before leaving to join ​Bayern Munich in 2013. The Borussia Dortmund attacker, who returned to the club in 2016, lauded the 51-year-old’s man-management skills, but says he could be ‘intimidating’ at times when he was a youngster.

“There’s a very serious side to Jurgen,” he told The Players TribuneWhen I was 17 or 18, and not giving 100 per cent in training, he could be so intimidating. He used to come running over and get right up in my face and start shouting at me."

“I can’t really translate from German perfectly, but you know how he talks, with his teeth grinding. Something like: ‘You have to have more passion! You have to give everything! ****! Come on!!!’”

Gotze, though, is eternally grateful for the faith Klopp showed in him – especially at such a tender age. “It’s funny to see him now with Liverpool because he’s such a natural guy in front of the media,” he added.

“He’s so authentic and he says whatever he wants. But I think most people just see the version of him standing on the touchline. Then after training, he would be completely calm again, and he’d take you aside and say, ‘Mario, how are you? Let’s talk about life. What’s happening?’