Mats Hummels, now at Bayern Munich, was a defensive stalwart for Borussia Dortmund during their most successful period in recent times, under Jurgen Klopp, and now he has revealed all on the current Liverpool manager.
"It was almost like family between us,’ Hummels said to the 'Daily Mail'.
"Of course we had our issues from time to time. One day we would be there, screaming at each other. But the next day? It was all fine. He understood me, I understood him.
"Each of us would know why the other one would act like he did. We never, ever had a big problem. He always considers what you say. He doesn’t always agree and he has the final word. But he considers it and he will say 'OK' or… 'Think about it again.' He is the boss."
Hummels went on to talk about Common Goal, a scheme set up by Juan Mata in which footballer donate a percentage of their wages to charity. Hummels has previously done work for UNICEF and it is a cause that resonates with him.
"Juan is someone who I admire, as a person and a footballer, so it was very convincing for me," he continued. "I want to be part of it. Maybe if this helps getting more players and personalities from football in there, good. So far it has worked out really well.
"There are times when I like typical things: Instagram and having a good time. But there are times when I want to help and I try to combine these things. Not everyone is the same. For me, to balance it all, it is important. And I’ll keep on saying what I think."