Back then, Klopp had made a promise: if Mainz failed to secure promotion to the Bundesliga, he would come to coach Dortmund.
So, as the two sides discussed working together again, they were already quite familiar with one another.
For Klopp, Dortmund was a much bigger and more prestigious club than Mainz.
Interestingly, both clubs shared the same anthem: "You'll Never Walk Alone."
But the situation now was completely different from a year ago.
"Hummels played well for us last season. Bayern wanted to bring him back, but the player refused their request. He doesn't want to return to Bayern."
Sporting Director Zorc was briefing Klopp on the club's current transfer dealings.
"We've reached a preliminary agreement with Bayern. They're willing to sell Hummels to us for 4.2 million euros."
Hummels had been Dortmund's starting center-back last season.
Especially in the second half of the season, he, Subotic, and Santana formed Dortmund's central defensive trio.
