RB Leipzig will meet Paris Saint-Germain in the UEFA Champions League semi-finals on Tuesday. Dayot Upamecano's defensive stability and Julian Nagelsmann's tactical genius are just some of the five reasons the Saxony upstarts will prevail.

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1) Mixing it with the big boys

Leipzig were only promoted to the Bundesliga in 2016, but in four short seasons they already look like something approaching the finished article. Despite significant financial backing, Die Roten Bullen have invested wisely in promising young talents with their best football still ahead of them, and this year they put Upamecano, Timo Werner et al under the tutelage of Nagelsmann, arguably the brightest young coach in the game.

Leipzig's average age was just 24 in the 2019/20 campaign, with goalkeeper Peter Gulacsi the only first-team regular who had already celebrated his 30th birthday. All but Patrik Schick and Christopher Nkunku are in at least their second season with the club, meanwhile. The result has been a well-oiled machine, the constituent cogs of which are all clicking into gear all at once.

Watch: A tactical look at Leipzig's counter-pressing

Leipzig served notice of their big-game credentials when they held Bayern Munich to a goalless draw in February. Germany's record champions plundered 100 goals this season, and remain among the favourites to win the Champions League having already sealed the double of Bundesliga and DFB Cup, but there was no way for them past Leipzig - the only team who managed stop Hansi Flick's side from scoring this season.

Over the course of the next month, Leipzig unceremoniously dumped 2019 runners-up Tottenham Hotspur out in the Champions League round of 16 with a 4-0 aggregate win, and although top scorer Werner had left for Chelsea by the time the quarter-final with Atletico Madrid rolled around, Leipzig still had the personnel and tactics to outplay the three-time finalists on Thursday, winning 2-1.

PSG might have seemed like a glamour tie not so long ago. Now, Leipzig can view their scalp as just another potential trophy on an increasingly cluttered mantlepiece.

2) Upamecano vs. Mbappe

Leipzig have such an even spread of talent throughout their squad, but with Werner having swapped Saxony for South London, Upamecano now finds himself as something of a first among equals at the Red Bull Arena. The young Frenchman's performance against Atletico was a sight to behold.

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Upamecano won 100 percent of his challenges, completed 92 percent of his passes, and kept Atletico's Diego Costa in his back pocket throughout. Five clearances and 99 touches of the ball were both game highs from Upamecano, and his performance had the great and good of the game tweeting their appreciation.

Rio Ferdinand and friends might have witnessed Upamecano at close quarters for the first time, but his talent was not so secret at Leipzig, and especially not for Werner. In Upamecano's first training sessions, Werner tried to do what he does to every other defender: knock the ball past him, turn the jets on, and meet it at the other side. It just didn't work against Upamecano.

"What's going on Timo?!" laughed then coach Ralph Hasenhüttl, now of Southampton. "Are you sick?!"

RB Leipzig have France U12 international Dayot Upamecano able to eavesdrop on Thomas Tuchel and his instructions for PSG players. - imago images

What Werner discovered then is something Kylian Mbappe might find out on Tuesday. Another speed merchant, Mbappe clocked 22.4 mph for PSG in 2019/20, as well as helping himself to 26 goals in all competitions, but he is only just over an ankle injury, trying to outrun a player who despite having significantly more muscle mass is yet to come off second-best in a footrace.

3) Apprentice better than master?

At least as far as the Estadio da Luz dugout is concerned, this particular Champions League semi-final can be considered to have been made in the Bundesliga. Nagelsmann and his opposite number Thomas Tuchel go way back, both once aspiring Augsburg centre-backs whose coaching careers far surpassed their playing ones almost as fast as an Upamecano sprint.

Tuchel called time on his playing career in 1998 and nine years later found himself in charge of Die Fuggerstädter's reserves, and a 19-year-old Nagelsmann. The youngster suffered a knee injury in that first season, though, and soon realised a professional playing career would be out of reach. Still under contract, Tuchel repurposed Nagelsmann.

"I started scouting opponents for Tuchel," the now 33-year-old explained. "Of course, I'm very grateful to him for, let's say, giving me the idea of becoming a coach."

Thomas Tuchel gave Julian Nagelsmann his break in the world of coaching at Augsburg. - getty images

Since that idea was planted, shoots have been growing at a remarkable pace. While Tuchel has taken two full decades to reach a Champions League semi-final, Nagelsmann – who became the youngest coach ever to work in the Bundesliga at 28 – has arrived with 'just' 12 years of coaching experience under his belt, and with only 33 years on his passport.

Trophies may still be lacking on Nagelsmann's CV, but that might change in the span of two games. Besides, taking over a Hoffenheim team regarded by many as certainties for relegation and turning them into a Champions League team within 18 months is no simple task, and it duly earned him the award of Germany's Coach of the Year.

Nagelsmann studied Tuchel's playbook, made some adaptations and refinements and authored his own chapters which are delivering a delightful denouement.

4) History on their side

Granted, this is only Leipzig's second season in Europe's elite club competition, but considering they were only formed 11 years ago – starting out life in Germany's fifth division – to be on the brink of a Champions League final is nothing short of sensational.

Paris are not one of the oldest clubs in Europe by any stretch of the imagination, though, being founded just 50 years ago, and with 13 French Ligue 1 titles, nine French Cups and a UEFA Cup Winners' Cup in their trophy cabinet, they can be rather proud of what they have achieved.

No bull, Leipzig were only founded 11 years ago - Stuart Franklin/Bundesliga/DFL via Getty Images

Comparing the two in the context of recent campaigns, however, gives Leipzig reason to be proud themselves. Especially when it gets to the business end of the season.

Only once – to Marseille in the quarter-finals of the 2017/18 Europa League – have Leipzig lost a European knockout tie. Their 2-1 win over Atletico Madrid in the quarter-finals was their seventh knockout victory in eight attempts.

For all their ambition and desire to become Europe's number one club, PSG have come up disappointingly short in recent years, getting eliminated in the last 16 in each of the past three seasons, after making it as far as the quarter-finals in their previous four campaigns.

Marcel Sabitzer and RB Leipzg have only ever lost one game in European competition, and remain unbeaten in their UEFA Champions League history. - imago images

The French giants last reached the semi-finals in 1995, but that final step has proved elusive. Given Leipzig's knockout pedigree, that could well remain the case this year.

5) More insiders starting

Even more so in the time of games behind closed doors, where every utterance can be heard in the opposite corner of the field, it is no longer just the individual interlocutor understanding the orders being hurled from the touchline.

No longer drowned out by the din of tens of thousands of fans, every piece of instruction enters the public sphere as soon as they leave a coach's mouth, and being able to understand what those orders are is the first step towards devising counter-measures.

Since Leipzig have three native Francophones in their squad in Upamecano, Nkunku and Nordi Mukiele, the secret will soon be out of the bag. Considering Nkunku is also a product of the PSG youth academy, he is a step further ahead in awareness of how the Parisians tick.

Dani Olmo showed what RB Leipzig's attacking midfielders are capable of with his opening goal in the win over Atletico Madrid in the quarter-finals. - imago images

Thilo Kehrer may be the only German-speaking player out on the field in a PSG shirt, and while Julian Draxler and Eric Maxim Choupo-Moting could translate Nagelsmann's orders from the bench, it could take some critical seconds for his messages to be received – vital seconds Leipzig could use to their advantage.

With tactics likely to have a major say in the outcome, this is another area where Leipzig hold an advantage.

Quiz: Bundesliga teams in the 2019/20 Champions League!

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