Rangnick is hailed as the mastermind behind the high-press German coaching philosophy that has produced success for Klopp and Chelsea boss Thomas Tuchel, with the third German to coach a top English club getting a welcome from his soon to be touchline rival.
"I know him - but usually we don't talk about things that are not confirmed yet!" joked Klopp. "If you tell me that will happen, I might believe you.
"Unfortunately a good coach is coming to England, to Manchester United,” Klopp said.
"He's obviously a really experienced manager, built most famously two clubs from nowhere to proper threats and proper forces in Germany with Hoffenheim and Leipzig.
"There's a lot of different jobs in football but his first concern was always being a coach, being a manager and that’s what his best skill is, obviously.
"All the coaches in the world, we need time to train with our teams and Ralf will quickly realise there's no time to train because we play all the time, so that makes it a bit trickier for him. A really good man, an outstanding coach.
"Wherever he was, he did an incredible job. He started early as a very, very young man at Stuttgart, coaching the second team and going from there.
"He went to Ulm and took them to the Bundesliga which was absolutely insane at that time.
"We faced each other when I was a very young coach when he was at Hannover. They always played our opponent a week after (us) so he called me, the young manager of Mainz and asked plenty of questions.
"I was happy big Ralf Rangnick was calling me but he got all the information they needed - they got promoted, we didn’t, so he owes me still something. In the football world in Germany he is very well regarded, and rightly so."
Klopp went on to reflect on his side's start to the season and as he suggested their defensive record needs to improve if they are to push for the Premier League title.
"To be where we want to be we need a good balance in the team," he added.
"We score two goals in games but then we spoke about how many goals we had conceded the week before.
"It's not a crazy number for a team around the top of the table but we concede too many, that's why we need to be a well-balanced team.
"That we take the necessary risks for our offensive stuff but we protect as good as possible. We need a line as high as possible and we need to be at our absolute best in a defensive part of the game. Then there is counter-pressing as well, so then we are really difficult to beat.
"I don't compare us with the team last year or the team the year before, I just want to be as good as possible."