Borussia Dortmund CEO Hans-Joachim Watzke has admitted he tried to get Jürgen Klopp to quit ​Liverpool and come back to the Westfalenstadion in 2018.

Klopp left ​Dortmund in 2015 after winning two Bundesliga titles, but after his departure, Dortmund were struggling under Peter Bosz who was sacked mid-season before temporary boss Peter Stoger attained a fourth-place finish.

It was at this point that the Bundesliga club's CEO, Hans-Joachim Watzke, put in a call to an all old friend in hope more than expectation.

Juergen Klopp

"I knew that Jurgen would [decline], that he will fulfill his contract in Liverpool," ​Watzke writes in his new book 'REAL LOVE. A life with BVB'.

"Jurgen has always fulfilled his contracts, but if you want to go new ways and we had to break new ground at BVB, then at least I had to ask Jurgen if he could possibly imagine that. I did not expect that at all, but I would not have forgiven myself for not asking him at that moment."

Klopp, however, turned down the offer, choosing to remain at Anfield.

“My phone rang while I was on the plane, Aki was on it: 'Jürgen, you have to come back’. I thought he was kidding," ​he recalls.

"Are you stupid, have you been drinking, how did you get the idea, I've got a few more years in Liverpool."

When asked if he would ever consider going back to Germany, Klopp said, “As a rescuer in need, if the club really needs my help - why should not I do that?

"It's very nice that I even have the opportunity. But, I admit, it does not seem so likely. There’s always something new to come."