It took Julian Nagelsmann a week to get over RB Leipzig's loss in the Champions League semifinals to Paris Saint-Germain. He talks through their wins over Tottenham Hotspur and Atletico Madrid with me on Zoom, and evaluates where they fell short against PSG; you can sense him playing the matches again in his mind.

Then he smiles, shrugs, says they're a young team, they'll learn... and you believe him.

Nagelsmann's age tags alongside him like it did for Mozart. Nagelsmann, 33, was the youngest manager in Champions League history to reach the knockout stages. He is just 33 years old! One of his players -- reserve goalkeeper Philipp Tschauner, 34 -- is older than him. The PSG team he lost to was captained by Thiago Silva, two years his senior. But for an untimely knee injury, Nagelsmann would still be out there playing rather than patrolling the touchline. As he admits without any air of arrogance, he was the youngest manager in Bundesliga history, and his success at Hoffenheim when he took up the reins there in Feb. 2016 paved the way for other, younger managers to follow suit.

It's a humbling experience listening to Nagelsmann, the coach who guided RB Leipzig to third in the Bundesliga and to the Champions League semifinals. In the Bundesliga, where the average age of managers is 49 years old, he rubbishes the notion that experience is key. And he also turns conventional football logic on its head.

Try formations. How does Pep Guardiola's Man City play? Usually in a 4-2-3-1. Jurgen Klopp's Liverpool? 4-3-3. Nagelsmann's Leipzig? "I do not prefer a formation because it is only numbers," he tells ESPN. "I do not think about formations too often. It is the easiest thing to recognize and to see on the pitch, but when the game starts is when things start to get weird."

How do you replace Timo Werner, their world-class striker who signed with Chelsea this summer? "You can't, but then I have to replace Patrick Schick as well."

Yep, forgot about him, the tall striker they loaned from AS Roma last season. (He's now at another top German side, Bayer Leverkusen.)

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Nagelsmann says all this in such a relaxed, offhand manner that you walk away from a conversation with him almost feeling like we've been taking football management too seriously, and it dawns on you that everything you thought you knew about football might, in fact, be wrong. Maybe you can be successful in management and fun -- Nagelsmann owns two skateboards, loves drones and is young enough to understand his players' own 2020 vernacular -- but there's far more to Nagelsmann than his affable, engaging, intriguing exterior.

Don't mistake his age for the joyful ignorance of youth: Nagelsmann has shown that he can stand toe-to-toe with any manager in world football.

It could have all turned out so differently for Nagelsmann. When he was just 20, his career as a promising centre-back was cut short due to injuries following a botched knee operation. He was devastated. He first looked outside football, at a business administration course at university. But Thomas Tuchel, now PSG manager, offered him an informal scouting role at Augsburg and it would be his first step on the road to coaching. First, he served as an assistant to Alexander Schmidt in 1860 Munich's Under-17 side, then left for a role in Hoffenheim's academy in 2010. By 2015, he'd been promoted to first-team manager, a role he took up in early 2016.

The appointment was greeted by the German press as "schnapsidee" (a decision made under the influence of alcohol), but he proved any doubters wrong and guided Hoffenheim, a mid-table team with reasonable resources, into the Champions League. People took notice.

"When I started I was the only young one, and I did well, and it opened the door for other young managers," Nagelsmann said. "I was, I guess, a role model. The club were brave to put me in charge of that professional team and then others recognised it could be possible to work with younger managers. But then if I lost every game at Hoffenheim, we wouldn't have been successful, that's it." He laughs as he trips up over the word "successful" in his second language.

That's part of his charm: he's happy to be vulnerable in front of his players. Nagelsmann's relationship with his team is interesting, too. Despite being in the same age range as most of them, he likes it. Younger players can learn quicker, and he can relate to them more readily.

He's also renowned for his adventurous use of new-age technology. At Hoffenheim he installed a massive screen on the training pitch so they could do real-time analysis; he brought in drones; he also used something called the "Footbonaut," a machine geared towards improving a player's first, second touch and spatial awareness. But his coaching philosophy and approach comes down to two fundamental pillars: efficiency on the field, and a personable approach off it. He sees his role as 30% tactics and 70% social competence.

His coaching philosophy stems partly from those managers he has worked under -- like Thomas Tuchel at Augsburg, but also his managerial hero, Pep Guardiola, and then from the grandfather of "gegenpressing," Ralf Rangnick. He was Nagelsmann's predecessor at Leipzig and also coached at Hoffenheim from 2006 to 2011. At Leipzig, Rangnick took charge for the 2018-19 campaign so the club could wait to bring in their long-term dream manager: Nagelsmann.

Rangnick's gegenpressing theories influenced Klopp's philosophy and tactics at Liverpool, Tuchel's at PSG and others around the world. When Nagelsmann took over Leipzig, he tried to build on the work Rangnick had already introduced: "I got used to Ralf's philosophy at Hoffenheim. Counter-pressing is a very important topic. Putting pressure onto opponents almost every single minute so we can win the ball... but that is only one thing, we need to find a good balance between ball possession and attacking moments."

Nagelsmann then dives into his own priorities for Leipzig. "Looking at the direct way when we have numbers up, numbers down, whether to counter-attack or whether to stay in possession." Anchoring all this is his awareness of the brutal season ahead, as Leipzig will likely be juggling the Bundesliga, the DFL Cup, the Champions League and the lack of a winter break.

"If you imagine we play every three days, you cannot work at that level every day, so we need time when the ball is at your feet, creating chances through ball possession. I try to find a good balance between all the phases, while also trying to develop new things."

And then married with this is how he gets the messaging across. He likes to overwhelm the players with information. "It is important that sometimes in training they are overloaded so they can improve; it is one of my ideas to do it like this and at the end players develop how I want them to develop." Yet he's not a tyrant, immune to feedback. "It is always key for the manager to look at the character of a player. It is important... that you have a good social feeling with the players and a good connection."

His players refer to him in the more informal "Du," rather than "Sie" -- the latter is normally used when addressing with respect (both translating as "you"). "If they love to go to training then they will develop a bit better, rather than they come to the training pitch and think 'I have to meet the manager again' and 'that he is a crazy guy'," Nagelsmann continues. "The social part is very important, but at the end it is also getting the idea of how they want to play soccer.

"You've got to find a good balance and have a good relationship with your players while still trying to improve them in all things soccer and what you will see on the pitch."

For his own development, he laughs at the question whether it's better to be a young or an old manager.

"I don't know because I've never been old as a manager... I don't know what is better because I am young, and I like to be young and try to stay young. It means I can understand my players better so perhaps it could be an advantage? At the end I want to get more games like my young players, like the team..."

As he looks back to last season where Leipzig finished third in the Bundesliga, he frequently re-iterates how they are a youthful group, but also how he's still learning on the job. At the halfway point of the season they were top of the league, but their form dropped off post-lockdown and they went winless in their final five home league matches.

"It's always interesting for a young manager to be a good competitor in the Champions League... to deal with the biggest teams in Europe, to watch their games and try to find a good match plan that fits your guys; to deal with these tough and strong personalities on the sidelines, like Diego Simeone or Thomas Tuchel, it is still a special situation." And then having looked backwards, it's time to focus forwards and how he's going to juggle replacing Werner, the interest in his best players and Bayern Munich.

Nagelsmann is also glowing in his praise of Bayern's Hansi Flick, impressed by how he successfully "managed the social parts of the dressing room" to turn around their campaign last season and win the treble. "I think it's not easy to catch them," he says of Bayern. "They have very good players, but also do great things in the transfer market."

He points to how Bayern have recruited well and built a pathway ensuring they have ready-made replacements for their older players already in the club. "They have money, quality and mentality. Our aim is to still reach the Champions League next season, that is more important than to catch Bayern... we always try to do this, but it is not easy."

And all this without Werner. Nagelsmann & Co. now have to find a way to replace his 28 goals in 34 league matches last season.

"Timo has a lot of capabilities; with that, it is hard to find a new like-for-like player," Nagelsmann said. "We have a success in [new player] Hwang [Hee-Chan, from RB Salzburg], who makes a lot of runs behind the defensive line. We also need a player to replace [Patrick] Schick. We need a physical forward who can be a replacement for Patrick; we also have good midfielders who didn't play as much last season due to Timo or Patrick. Last season we bought Dani Olmo and we knew he wouldn't play as much, but he is in top shape and I'm happy with him. We have [Christopher] Nkunku, but we need more players to replace Timo because like for like is not possible."

Leipzig have already lost one of their best players in Werner, but they're not about to lose another in Dayot Upamecano. The much-coveted central defender is on Manchester United's radar, but Nagelsmann is adamant the 21-year-old will stay at Leipzig for another season.

"It is a big topic and focus for us -- there will be clubs focusing on [Ibrahima] Konate, [Dayot] Upamecano and Nkunku. These are talented guys. It is hard to progress and replace them every season, but it is important to progress. We have to try and find successes for the future."

And what about his own future? Real Madrid's interest in Nagelsmann was well-known, but he turned down their advances in 2018. He is much admired around Europe, but equally, he's in no rush to move, nor does he want to grow old in the coaching role.

"I could not imagine coaching for the next 30 years... You have no time for family or other hobbies." There's an idealistic hope of retiring to the Alps with his family and indulging his hobby of snow sports, perhaps even being a guide. But with Nagelsmann, there will inevitably be a new innovative thought or project that keeps him coming back to football.

"Soccer is a fast business, I try to plan, and I know I'm young. You have to do something to get better, I could not imagine managing for 25 to 30 years, but I could win my first title, and get hungrier and hungrier and want to win more titles so you never know?"

And with that, Nagelsmann is getting ready to head to training. Leipzig will be fascinating this season, and thrilling to watch. It's hard to predict exactly how they'll fare in the post-Werner era, but Nagelsmann will have a plan. Just don't try and second-guess what formation he'll use.