Borussia Dortmund and Bayern Munich - has the balance of power changed?
For years Bayern Munich have been dominating Borussia Dortmund on and off the pitch.
They have won six titles in a row, finishing 25 points or more above Dortmund on three of those occasions - including last season.
On top of that, they have cherry-picked some of Dortmund's star players over the past six seasons.
But now - with a team full of talented youngsters - Dortmund are the unbeaten Bundesliga leaders, with Bayern nine points behind them in fifth.
The managers -'Favre has done everything Kovac hasn't been able to'
Both clubs appointed new managers this summer with Dortmund going for experienced Nice boss Lucien Favre, who previously managed Hertha Berlin and Borussia Monchengladbach in the Bundesliga.
Bayern went for their former defender Niko Kovac, 47, who was managing Eintracht Frankfurt. His only trophy as a manager was in his final game - against Bayern - in last summer's German Cup final.
Kovac has lost only three of his 20 games, but he took over a team who finished 21 points clear of anyone last season. Favre has won 14 of his 19 games, losing only once - in the Champions League.
"When it comes to breaking down well organised defensive teams, you can almost see the Bayern players looking to the touchline thinking 'what are we doing, what's the idea here?'," German football journalist Raphael Honigstein said on BBC Radio 5 live's Football Daily European show.
"That's where Kovac has been found wanting. It's not a personal issue so much as a team not quite believing he can really help them in what they need most.
"That breakdown in trust, even if it's only based on technical issues, might just be unbridgeable as far as his long-term future is concerned.
"It's so difficult for any coach, especially someone like Kovac who has never worked with players of this calibre before. He's a relatively inexperienced manager who has only tasted success at Frankfurt last season with the German Cup. It might prove beyond him - that's the big worry.
"To have a Bayern manager in November being judged game to game, day by day almost, speaks to the precariousness of the situation. It's not really a sustainable way of conducting business."
But Dortmund - who only got into the Champions League places on goal difference last season - are doing much better than many people thought possible.
"Lucien Favre has done everything Kovac hasn't been able to do," said Honigstein.
"He's improved the team collectively and individually overnight. Every single player is doing much better than last year. They are unbeaten domestically, seven points clear and scoring for fun."
One area Bayern have outperformed Dortmund this season, albeit only slightly, is in the Champions League. Both teams are into the last 16 but Bayern are top of their group and unbeaten, with Dortmund second in theirs.
The players - 'Bayern transition will be very difficult'
Dortmund's squad is full of skilful youngsters with squad regulars Jadon Sancho, Jacob Bruun Larsen, Christian Pulisic, Dan-Axel Zagadou and Achraf Hakim all aged 20 or under.
England winger Sancho, 18, has scored five times and set up another eight this season. Paco Alcacer, a summer signing from Barcelona, has scored a goal every 52 minutes - 10 goals in 10 games.
Bayern are well documented as needing an overhaul. Six of their regular team are in their 30s, with wingers Arjen Robben and Franck Ribery 34 and 35 respectively.
"Of course, when Robben is in the mood, fit and given space, and Ribery has a lot of time, they can still individually do a lot of damage," said Honigstein.
"What Bayern didn't anticipate is how tough it would be for Niko Kovac to manage all that in the dressing room - managing the transition with the personnel, with the egos."
And the German journalist is not sure they will find it easy to improve their squad sufficiently.
"I still believe Bayern with this big transition just ahead of them will find it very difficult to sell themselves to anyone," he said.
"If they try to buy Ajax pair Matthijs de Ligt and Frenkie de Jong and say 'come to us, you'll improve under this great manager, we have this great team', all these things don't exist. It makes the transition very difficult."
The boardroom - 'Power structure at Bayern is broken'
For years Bayern have been the dominant force on and off the field in German football.
With the biggest budget - and best chance of silverware - they have signed Mario Gotze and Robert Lewandowski - on free transfers - and Mats Hummels for a reported £30m - in the past few seasons from Dortmund.
Dortmund won their most recent title in 2011-12, the last team other than Bayern to win the Bundesliga. But times are changing.
"The power structure at Bayern is broken," said Honigstein. "[President] Uli Hoeness and [chief executive] Karl-Heinz Rummenigge are the two people in charge. They've always had issues with each other but they've managed to agree to disagree and find enough common ground.
"But right now with a very weak sporting director Hasan Salihamidzic and a fairly weak manager, there's too much weakness and discord.
"They've gone from a team who had Matthias Sammer as sporting director and Pep Guardiola as coach in 2015-16 to a team who have Kovac and Salihamidzic and that lack of authority and competence has exposed some of the other fault-lines in the club. It's why they're struggling, not just on the pitch but off it.
"Not only are Dortmund doing so much better on the pitch, they also seem to have done their homework. They look like the team ahead of the curve. They have learned the lessons of last year's disaster, they have strengthened really intelligently, changed the hierarchy, the dynamics, the power structure in the dressing room and above.
"They brought in Sammer as an external consultant, and Sebastian Kehl, the former Dortmund and Germany player, as the Dortmund version of Salihamidzic but he's doing a great job.
"The idea that they're more strategically smart, more clever and competent when it comes to organising themselves is really the biggest issue for Bayern.
"Even when Bayern were doing badly they could always pride themselves on having the bigger machine. But right now Dortmund have the smarter machine."