Klopp's decision has generated controversy from a host of figures including one of his former players at Dortmund.
Kevin Grosskreutz said: "I woke up, I had 30 messages on my phone and I thought: What happened? I thought I was dreaming, then I hoped it was fake news. Two hours later it was official. It was pretty shocking and sad. Somehow it hasn't really sunk in yet.
"I don't think anyone was expecting it. It's very, very strange and I can't really comprehend it yet. It's like shock! Nevertheless, he's a friend of mine and I owe him a lot. And I will always be grateful to him. As a football fan, I think it sucks, to put it bluntly! But as a friend, you have to accept decisions being made. When we meet, I'll still tell him personally that I think it's sh*t that he does something like that!”