Having already outwitted Jose Mourinho and Diego Simeone in the Champions League, RB Leipzig boss Julian Nagelsmann now faces Paris Saint-Germain and Thomas Tuchel, who helped spark his coaching career 12 years ago, in Tuesday's semi-final.
The 33-year-old Nagelsmann is the youngest coach to reach the last four of the Champions League, underlining his reputation as one of Germany's brightest tacticians in Leipzig's first appearance in the competition's knockout phase.
Nagelsmann got the better of Simeone's Atletico Madrid in a 2-1 victory Thursday, claiming another famous scalp following the disposal of Mourinho's Tottenham -- last year's runners-up who were beaten home and away in the last 16.
Next up is PSG and fellow German Tuchel, under whom Nagelsmann took his first steps into coaching for Augsburg's reserves in 2008 after a persistent knee injury forced him to retire aged just 20.
"Of course I was his player, but that was many years ago," said Nagelsmann, a decent centre-back in his youth.
"I'm more into the day-to-day business now, just like him."
- 'Never been close' -
As coach of his ex-club Hoffenheim, Nagelsmann lost twice and drew against Tuchel, then in charge of Borussia Dortmund in the Bundesliga between 2016 and 2017.
"Matches against him are always interesting, because he has a good idea about football," added Nagelsmann.
"I have often played (as a coach) against him (Tuchel) but rarely won. That should change now," he added.
"It's clear the quality they (PSG) have - Angel Di Maria will be back and (Kylian) Mbappe will be fit enough to start.
"We will need a top performance to reach the final."
A knee injury cut short his playing career in 2008, "otherwise I would have needed an artificial knee when I was 40," said Nagelsmann.
Barely out of his teens, he was offered a scouting role by his Augsburg reserves coach Tuchel.
"It was a pragmatic decision - since Augsburg were still paying me, I spotted opponents for Tuchel," Nagelsmann said in a 2015 interview.
The pair have "never been extremely close", revealed Nagelsmann.
"He wasn't my mentor, even if many refer to him as one.
"Our relationship was too pragmatic for that, but I am grateful for him giving me the idea to become a coach."
Tuchel went onto to work at Mainz and Dortmund, who he steered to the 2017 German Cup title before joining PSG in 2018 and winning back-to-back French league titles.
All the while, Nagelsmann gained experience coaching youth teams at Augsburg, 1860 Munich and Hoffenheim before moving to Leipzig in 2019.
After coaching their Under-17 team, Nagelsmann rose up the ranks in Hoffenheim.
He became the youngest head coach in Bundesliga history in February 2016, aged just 28, when Hoffenheim were second from bottom in the table, but he kept them up to earn the accolade of Germany's coach of the year.
Under Nagelsmann, Hoffenheim managed top-four finishes in the following two seasons, earning a debut Champions League campaign in 2018/19 but making a group-stage exit.
He turned unfancied Hoffenheim into a side capable of twice beating mighty Bayern Munich, the icing on the cake being a 2-0 away win at the Allianz Arena in 2017.
Success with Hoffenheim attracted Red Bull-backed RB Leipzig, who Nagelsmann joined before the start of this season, finishing third in the Bundesliga.
- 'Heavy burden' -
Now more than a decade after their time in Augsburg's reserves, Tuchel and Nagelsmann clash for a place in next Sunday's Champions League final.
However, the Champions League is "not about duels against Mourinho, Simeone or now against Tuchel," insisted Nagelsmann.
"It's a team sport, and the team (Leipzig) has played outstandingly well."
Nagelsmann believes PSG's quarter-final win over Atalanta lifted "a heavy burden" off Tuchel who was under pressure to make the last four.
"I'm happy for him."
However, any cordial exchange with Tuchel before kick-off will merely be a facade, Nagelsmann insists.
"That's what the media would like to see, but that doesn't exist in the real football world."