Borussia Dortmund's meeting with RB Leipzig at the SIGNAL IDUNA PARK on Matchday 19 provides a host of contrasts and throws up a number of questions, notably: can the visitors add weight to the argument they have usurped their hosts as FC Bayern München's main challengers?
Second-placed Leipzig, two places but a mammoth 11 points ahead of Dortmund, have the upper hand coming into the fixture, particularly as they also won the team's maiden meeting this term.
bundesliga.com weighs up the two rivals ahead of Saturday's titanic showdown (kick-off 18:30CET).
Watch: Five things on Dortmund vs. Leipzig:
Traditionsverein vs. New Kids On The Block
Dortmund fans made their views on Leipzig's claim to a seat at the top table of German football clear when they refused to travel east for the teams' maiden meeting - and RBL's first-ever Bundesliga home game - on Matchday 2. With the Yellow Wall of the Südtribüne behind them, BVB often have a second and third wind, but Leipzig fans will not snub their team's trip to the Ruhr with some 8000 expected, a club record for an away game. They may be just a drop in the 80,000-capacity ocean that is the SIGNAL IDUNA PARK, but they will undoubtedly cause waves.
Watch: Discover the allure of Dortmund's world-famous home ground:
BVB Dortmund vs. RB Dortmund
Those who do pack into the stadium to see the game on Saturday will no doubt remark that, despite their very different histories, the sides bear similar traits on the pitch. In fact, Leipzig will be using tactics closely resembling those first put to great effect by Die Schwarzgelben under Jürgen Klopp and since refined and reprised by Thomas Tuchel. "It will depend on whether our pressing game works perfectly. So we'll need players who'll be ready to put in the leg-work," said Leipzig boss Ralph Hasenhüttl in his pre-match press conference. However, the absences of Timo Werner (flu) and Emil Forsberg (suspension) are a major handicap to the visitors in their ambitions to beat BVB by 'doing a Dortmund'.
Watch: Highlights of Leipzig's swashbuckling win over Hoffenheim:
Weigl vs. Keita
With Julian Weigl and Naby Keita both 21, this is likely to be a duel that will have a number of thrilling sequels. In themselves, they embody their team's philosophy: Weigl unruffled, cool and stylish in possession; Keita, all high-octane energy and power, cut with a touch of class. The Dortmund No.6 will almost certainly come face-to-face with Leipzig's midfield live wire as he fizzes from box-to-box. Which of the pair can smother the other will have a major bearing on where the points go.
Watch: Naby Keita scored a dramatic winner against BVB on Matchday 2:
Battle of the ages
The adage of 'if you're old enough, you're good enough' could be the motto of both these clubs for whom youth is their lifeblood. Leipzig's well-documented policy of not signing players over the age of 24 means they possess the youngest squad in the Bundesliga. The no-fear mindset they have played with up till now this season means they are likely to be inspired rather than overawed by the intimidating atmosphere they will face. As Hasenhüttl said, such experiences are "what we play for." Dortmund, though, have fielded no fewer than six players under 21 this season already, and with the likes of Christian Pulisic (18) have baby-faced starlets who could give RBL a testing time.
Watch: Christian Pulisic is not the only Bundesliga star in a state of BunDucksLiga fever:
Tuchel & Hasenhüttl
Thomas Tuchel might have been on the opposite bench on Saturday had talks in summer 2015 led to him taking the Leipzig job. Dortmund's gain has not, however, proven Leipzig's loss, with Hasenhüttl again proving his ability to step up as he first did with VfR Aalen and then FC Ingolstadt 04, leaving his BVB counterpart trailing in his wake this term, and inspired by Tuchel's predecessor. "It was fascinating to see how a team, which didn't have the best individual players, could still become German champions," Hasenhüttl said of Klopp's Dortmund earlier this season. With just three points between the Leipzig boss' team and leaders Bayern ahead of Matchday 19, perhaps a young coach will be saying the same thing of Hasenhüttl in the future.
Watch: Four of Tuchel's Dortmund charges made our 2016/17 Team of the Hinrunde: