Harry Kane didn’t play against Saarbrücken on Wednesday, but it didn’t stop him becoming the butt of the joke. As his Bayern Munich side went down 2-1 in the second round of the DFB Cup against their unfancied third-tier opponents, Kane remained on the bench, watching another trophy slipping out of his grasp. His first game at Bayern had ended in defeat in the Supercup. Meanwhile, the Spurs team he left in the summer are top of the league. Sometimes, the random scrawl of footballing fate can read suspiciously like poetry. Still, one of the advantages of playing for Bayern is that salvation is always close at hand. In a way the defeat in midweek, with Eric-Maxim Choupo-Moting flailing away up front, proved exactly why Kane was signed: the touch of class, the cutting edge, the point of difference. This season has already produced 14 goals in 13 games, two hat-tricks, and an outlandish lob from his own half against Darmstadt last weekend. Yet to a large extent all this feels like mere preamble to his first big test on Saturday evening. In the words of Sebastian Kehl, the Borussia Dortmund sporting director: “It’s that time again.” To Dortmund, then, a club to whom Bayern have not lost to in four years, but who will begin as slight favourites against a Bayern side who travel in a rare state of disarray. The cup defeat has crystallised some of the more nebulous sensations of discontent around a club whose aura of invincibility – buttressed of course by those 11 straight titles – has rarely seemed more fragile. “We’re going to Dortmund to win,” wrote Thomas Müller in his newsletter this week (and of course Thomas Müller has a newsletter). “Even if we know that the grapes tend to hang higher there than in other Bundesliga stadiums.” But Bayern’s problems begin at the back, where Kim Min-jae is potentially the only fit senior centre-back. A knee injury has put Matthijs de Ligt out for the next few weeks. Dayot Upamecano has not played in a month and is still doubtful. Konrad Laimer has been filling in at the back but may well be needed in midfield with Joshua Kimmich suspended and Leon Goretzka and Raphaël Guerreiro struggling. There has even been some talk of a desperate SOS to their 35-year-old former defender Jérôme Boateng, without a club after leaving Lyon in the summer and who has been training intermittently at Säbener Strasse this season to keep fit. Really this predicament seems to capture the wider puzzle of Thomas Tuchel’s Bayern, a club being held together with short-term fixes and occasional bouts of individual brilliance. Eight months into Tuchel’s reign it remains hard to discern exactly what the big idea is, beyond a little more solidity off the ball, a slightly deeper press and the occasional use of Kane as a withdrawn forward and a platform for counterattacks. They remain unbeaten in the league. Performances have been OK. But at a club of Bayern’s size this has never been enough on its own. Inevitably, the first signs of frailty have been accompanied by the usual noises in the media. We are told that Bayern’s players are growing increasingly dissatisfied by the lack of progress, Tuchel’s supposedly aloof manner, and his apparent tendency to anoint favourites. We are told that Tuchel is in constant conversation with stars such as Kane and Leroy Sané but that others are distanced to the extent that they only discover from the assistant coach, Zsolt Low, that they are not in the side. Most likely this is the usual mixture of rumours, slurs and grinding axes. But Tuchel will know better than anyone that when the cracks begin to open at any big club, they do not open slowly. The irony here is that Bayern’s troubles have simultaneously heaped the pressure on Dortmund, who have started the season with an encouraging defensive solidity under Edin Terzic. “If you don’t beat them now, you’ll never beat them again,” the former Germany international Dietmar Hamann quipped during the week and, despite an abject recent record in this fixture, Dortmund are in the curious position where a draw would probably be seen as a missed opportunity. Of course the heartbreak of last season’s final-day collapse, when Dortmund needed a win to clinch the title but could only draw 2-2 at home to Mainz, remains fresh. They lost Guerreiro and Jude Bellingham in the summer while Bayern signed Kane, and for the Bundesliga as a whole there is a sense that the competition needs a genuine counter-narrative to the saga of Bayern dominance. “The desire for a new champion is great almost everywhere in the country,” the Dortmund chief executive, Hans-Joachim Watzke, says. “Financially we are not on equal terms, and will not be able to reduce this gap in the coming years.” A Bayern victory would open a five-point gap between the teams, even if Xabi Alonso’s sparkling Bayer Leverkusen remain the autumn pacesetters. Of course it is too early in the season for definitive statements, for lines in the sand, too early even for revenge. But if Dortmund have learned one lesson the hard way over the past 11 years, it is that when you have a chance to kick Bayern when they’re down, then you need to take it.