Mario Gotze has hailed Jurgen Klopp's 'personality' as he recounted a story about when his former Borussia Dortmund manager had a hair transplant.
Germany's World Cup winner was handed his professional debut by Klopp when he was a teenager and became a key part of the Dortmund side that won back-to-back league titles.
He insists it is the Liverpool boss' humour that separates him from the rest of his managerial rivals.
'He knew how to handle me. He was an outstanding coach, but his personality was the most important thing for me as a young player,' Gotze wrote in the Players' Tribune.
'I have never met a manager in football who was so naturally funny. I will never forget the time I ran into him in Dusseldorf during the summer. He was going to see the specialist there to have his hair transplant done.
'This became big news in Germany, but he was so funny about it. He was smiling, telling me all about it — how cool it was going to look and everything.
'And then as he was leaving, he just gave me a wink and he said, 'Mario, don't worry, I will save the phone number.'
'I said, 'What do you mean?'
'He said, 'The doctor's number. I'll save it for you. In a few years, you might need it.'
Gotze made his senior debut for Dortmund in August 2010, at the start of Klopp's first title-winning season in Germany.
The 26-year-old stayed at Dortmund until 2013 before he left for Bayern Munich on a free transfer in controversial style.
He returned three years later but only after he was heavily linked with a Klopp reunion at Liverpool.