It will be master against apprentice when Liverpool manager Klopp welcomes Wagner's Huddersfield to Anfield on Saturday – the first competitive meeting between the two Germans.
Wagner and Klopp first met as players at second-tier German side Mainz in 1991, before working together at Borussia Dortmund, and the Terriers boss is relishing the opportunity to go toe-to-toe with the Liverpool boss.
"It is extraordinary because he is my best friend," said Wagner via the Telegraph.
"But the real extraordinary story is that Huddersfield are playing Liverpool in the Premier League."
Wagner was appointed Huddersfield manager in 2015 and by May this year, the 46-year-old guided the Yorkshire outfit win promotion to the Premier League for the first time.
He now takes his Huddersfield side to Merseyside on the back of a stunning 2-1 victory over Manchester United last week, which moved them within a point of ninth-placed Liverpool.
"Did I think I would play him in the Premier League two years after arriving here? It is at least 10 years sooner than I ever dared dream," Wagner continued.
On Klopp and Liverpool, Wagner said he knows what to expect, adding: "For the first time, my very good analysis team came to me and I tell them, 'Don't tell me, I know'.
"It makes it easier to play them because I don't have to invest too much time in analysis, I know all I need to know about them and how he will set them up."