RB Leipzig's meteoric rise from the fifth tier to the UEFA Champions League semi-finals has caught the attention of the footballing world, including that of German juggernauts Bayern Munich, who have seen a new rival quickly establishing themselves in the Bundesliga and beyond.
Few teams have been able to keep pace with Bayern in the Bundesliga down the years. Borussia Mönchengladbach did it during the 1970s, Hamburg managed it for parts of the 1980s and, more recently, Borussia Dortmund have regularly challenged the imperious authority of the Munich giants.
Leipzig, though, came equipped to push the record champions from the very start and for the foreseeable future.
Bayern and Leipzig went into each of their Bundesliga meetings across the last two seasons as the top two. It's become a common configuration in clashes between the title rivals and while it won't be the case in 2020/21, we're being treated to the mammoth clash only four weeks into the season. It all began back in December 2016 when Die Roten Bullen paid their first visit to Munich to take on the champions...
The Saxony club had just completed their seven-year climb from the fifth tier to the Bundesliga and arrived in Bavaria not just as top-flight newcomers, but level on points with Bayern at the top of the table in the final game before the winter break.
"We're going there to win," proclaimed Leipzig's then sporting director Ralf Rangnick.
Watch: Leipzig were blown away on their first visit to Bayern
Rangnick's prediction that Leipzig were "unlikely" to emulate Kaiserslautern and win the title as a promoted club proved accurate. Bayern's statement 3-0 win opened up a three-point gap that eventually grew to 15 by the end of the season, but with Leipzig finishing second only to Carlo Ancelotti's men, they had already delivered a statement of their own.
That final difference could have been nine points had Leipzig not squandered leads of 3-1 and 4-2 in their first-ever home meeting with Bayern on the penultimate day of the season, eventually going down 5-4 to the already-crowned champions in a barnstormer.
It was the same scoreline, albeit on penalty kicks, when Bayern beat Leipzig in the second round of the 2017/18 DFB Cup. It set the tone for guaranteed drama when these two meet.
Watch: Leipzig and Bayern produced an incredible nine-goal thriller in 2016/17
And they did so again just three days later in the first Bundesliga meeting of the season. It proved a rather simple three points for the champions under Jupp Heynckes as they ran out 2-0 winners at home, with Leipzig finishing with 10 men for the third time in four encounters. James Rodriguez and Robert Lewandowski wrapped up the points after an early red card for Leipzig captain Willi Orban.
A watershed moment followed in March 2018, though, as Ralph Hasenhüttl's side recorded their first victory over the runaway league leaders. Despite displaying symptoms of the dreaded 'second-season syndrome' and ultimately finishing sixth - a whopping 31 points behind Bayern - Leipzig still managed to come from behind to claim a 2-1 win at the Red Bull Arena thanks to substitute Timo Werner. Leipzig realised they could in fact beat Bayern, despite it being one of the record champions' most dominant recent campaigns.
Watch: Leipzig's maiden win against Bayern
As time has gone by, the on-field differences have reduced and the contests have become even tighter. In 2018/19, Bayern needed a late strike from substitute Franck Ribery to win 1-0 in Munich before a goalless draw of attrition in Leipzig. Although nine points off their opponents on the penultimate matchday, the Saxony upstarts will have seen it as a feather in their cap that they delayed Bayern's title win until the final day.
The world was then offered a taster for the coming title fights in the 2019 DFB Cup final. For Bayern it was a chance to reassert their domestic dominance by claiming a 19th cup title and 12th double. For Leipzig it was a chance to show the footballing world that they meant business by securing a first major honour, and doing so against Germany’s best team.
In the end, 3-0 perhaps flattered Bayern but it was a typically professional job from a team that has proven time and time again that they know how to win. That is where Leipzig want to be and they are making progress.
Closing the gap
Just a few days after that defeat in Berlin, Julian Nagelsmann, who had already been announced as the new Leipzig boss earlier in the season, took up his position at the Red Bull Arena. The youngest coach in the Bundesliga is also one of the most highly regarded and he arrived with the directive to win trophies.
It's not a case of Leipzig looking to knock Bayern off their perch, as a certain Sir Alex Ferguson might have put it, but simply to compete at the same level as the most successful club in Germany.
Nagelsmann's first match in charge of Leipzig against Bayern on Matchday 4 produced a fascinating spectacle. Lewandowski's early goal was the result of a defensive mistake and hosts Leipzig were lucky to be level at half-time when Emil Forsberg converted a penalty after a dominant first 45 minutes by the champions.
Nagelsmann, though, showed he's never afraid to react and made changes at the break. Leipzig performed much better and in the end, deserved to keep their two-point early-season advantage over the champions.
Watch: How Leipzig stopped Bayern's treble-winning juggernaut
Prior to Bayern moving back to the top of the league on Matchday 20, Leipzig had been above the champions in the table for all but four weeks. Although the gap after 34 games ended up at 16 points, there was little to separate the sides when they went head-to-head.
The season's second encounter at the Allianz Arena was another tactical battle. No defensive errors this time meant a 0-0 draw, although it was notable for Nagelsmann's match plan to press the champions as Leipzig - on their fourth visit - avoided defeat at the Allianz Arena for the first time. In the end, it was a happy point for both sides as Leipzig became the only team to prevent Bayern from scoring - and winning - in 2019/20.
Last season the drama continued as, following on from that goalless draw, Bayern and Leipzig shared six goals in a 3-3 draw - with Thomas Müller grabbing the equaliser as Bayern came from behind twice. And then, as they so often do, Bayern travelled to Leipzig on Matchday 27 just four points clear of their hosts but produced a marvellous performance to come away with all three points in a 1-0 win, which set them on their way to a ninth straight Bundesliga title.
Watch: Bayern and Leipzig's emphatic 3-3 draw in 2020/21!
The rivalry of the future?
With over 70 pieces of silverware displayed proudly in their club museum, though, history is overwhelmingly in Bayern's favour. But for Leipzig it seems only a matter of time before they'll have a trophy of their own to parade.
This summer the rivalry was given a new flame as head coach Nagelsmann, midfield maestro Marcel Sabitzer and defensive powerhouse Dayot Upamecano all swapped Leipzig for Bayern. The trio will face their former employers on Matchday 4 of 2021/22, with Leipzig restocked and ready to battle for a title once again under American head coach Jesse Marsch.
Watch: Analysis - Leipzig vs. Bayern in 2021/22!
Is it now or never for Die Roten Bullen? No, it rather looks like now and forever as they start to pose a permanent threat to Bayern’s dominance in a way that few others have done before. They have learnt from every defeat and grown into their role of leading challengers.
Expect Bayern Munich vs. RB Leipzig to be a defining fixture in the Bundesliga and beyond for years to come.