At Dortmund, he took on - and toppled - the dominance of Bayern Munich, winning two Bundesliga titles and also took his team to a Champions League final.
Dortmund boast the highest average home attendance of any football club in the world, with average crowds of 80,000 for Bundesliga games.
Kearney was impressed by the whole experience, and particularly the openness of the man who has one of the biggest and highly-pressured jobs in world sport.
"I've been to football clubs and other sports [clubs] before where they don't give a great deal away but he was wonderful," said Kearney of Klopp. "Sometimes the person you are talking to can be a bit reluctant to open up but I thought Jurgen was very open and I found that very enlightening."
Kearney was particularly interested in finding out about player development, which Klopp excelled in at Dortmund and is a particular strength of German football.
"I asked about the academy and the way they develop the players in Germany," said Kearney. "It is a lot different to the way it is here in England. It was a wonderful conversation, really enjoyable."
Klopp had seen bits of the Rugby World Cup but this was his first taste of the 13-man code.
"He knew a little bit about rugby," said Kearney. "He watched us train for a bit and saw the contact. He got a little bit of an appreciation for it and I think he is planning on watching the game on Saturday [Sunday NZT]."
Kearney also revealed himself to be an English Premier League fan, though he has developed a habit of switching teams over the years.
"I am a big soccer fan," said Kearney. "A couple of years ago, I was riding Liverpool, last year, Chelsea, this year, I might stick with Arsenal. Back in my teenage days, I followed Spurs with Ossie Ardiles, Ray Clemence, [Glenn] Hoddle ... so I have a bit of background in English football."
Melwood is a remarkable facility. It features three full size pitches, including one the exact dimensions of Liverpool's Anfield ground (101m x 68m).
The pitches also feature full under-soil heating, so they can be used throughout the harsh winter months in the north of England.
Melwod also boasts rehabilitation rooms, a gym, swimming pool, press meeting room and restaurant.
The Kiwis enjoyed the experience, and even had an impromptu football session at the end of training.
Martin Taupau revealed a wicked left foot shot - sending one strike over the top of the towering perimeter fencing and on to another field - while Roger Tuivasa-Sheck, Adam Blair and Kodi Nikorima impressed with their juggling skills.
