German football has a long and distinguished tradition of "lucky garments", stretching from Peter Neururer's Mickey Mouse ties to Udo Lattek's famous blue jumper at Köln in 1987-88. But is there also a lesser well-known, much darker reverse to that superstition, a curse of an unlucky jumper, maybe? Yes, it seems far-fetched. But events at Schalke 04 on Saturday took such a dramatic turn for the worse in the last couple of minutes that a supernatural explanation cannot be ruled out.

Consider the evidence. The Royal Blues were drawing 1-1 with the bottom side Greuther Fürth when new recruit Raffael hit the inside of the post with three minutes to go. The ball bounced back into play. Five minutes later, Nikola Djurdic scored an unlikely winner for the visitors with a stooping header, from an offside position. Cue mass uproar and jeering in the "poisonous atmosphere" (taz) of the Veltins-Arena. "You are destroying [our] mythical club," read one banner. "The whole shop is about to explode," wrote WAZ. There's certainly a danger that Schalke's season will die on its knees. After an auspicious beginning, the Champions League is seven points away and Galatasaray will probably knock them out in the last 16, too. They have only won one of the last nine Bundesliga games.

The next day, "Keller out" banners were spotted near the training ground. Four games in, the interim coach, Jens Keller, is already perceived as out of his depth. There are parallels with Rafael Benítez's situation at Chelsea. Most neutrals are convinced that Keller, 42, knows his stuff but the supporters simply do not believe in him as a leadership figure. The former Under-23 coach at S04 lacks charisma and gravitas. What's worse, he doesn't seem to get lucky. And that's where the jumper hoodoo might come in. The former VfB midfielder took over from Christian Gross as caretaker of Stuttgart in October 2010. At the presentation, he wore a chequered brown and beige number that screamed loads of things – retirement home, medieval court jester, free jazz – except football manager. Keller never recovered from that false start and was replaced by Bruno Labbadia after two months of bad results.

Keller didn't wear said top again when the Schalke sporting director, Horst Heldt, surprisingly picked him to succeed Huub Stevens before Christmas. But somewhere, at the back of a wardrobe, and at the back of people's minds, that jumper must still be exerting a destructive influence. It might just be the perception that Keller is not quite cut out for the job but it is so strong that it affects reality. "He has come without any credit," wrote Süddeutsche Zeitung in an op-ed piece about Schalke's "mega-crisis". Keller is aware of his PR problem, too. "The team is intact but there's nothing I can do against the public's scepticism," he said.

"Embarrassing, a catastrophe," Heldt said about the listless performance against the weakest team in the top flight. But should he have known better? Firing Stevens, the iconic manager, had been a necessary evil, his gruff man-management had antagonised too many players. There's been no visible upturn since his departure, however, on the contrary. Schalke are unrecognisable from the side that dominated Arsenal at the Emirates in October.

Unless they start playing with a modicum of composure again very quickly, it will soon get to the stage that Keller will have to go as well but that move would severely undermine Heldt's own position. He needs Keller to succeed, in some shape or form, before he can embark on identifying a long-term successor. In the meantime, though, the Bundesliga's most self-destructive club is teetering on insurgency.

Schalke supporters made a point of cheering old boy Gerald Asamoah on his return to the Veltins-Arena with Fürth while their own players were booed. "You can't work here," said an angry Jermaine Jones. "There's always been drama in the six years I've been here, under any coach. It's natural that the team are low on confidence." A trip to the Allianz Arena is unlikely to improve the mood significantly before the Galatasaray match. The only good news after the latest bout of self-inflicted damage is that Schalke look well poised to defend at least one title this season – that of Meister der Schmerzen, champions of pain.

Talking points

• Life in the nether regions of the table cannot be too funny, especially if you are the vanity project of a billionaire. But the people at 16th-placed Hoffenheim obviously have a sense of humour: they demoted hapless keeper Tim Wiese to the stand "for his own protection" (sporting director Andreas Müller) and replaced him with Heurelho Gomes in midweek. The crowd's reaction in the Rhein-Neckar-Arena on Saturday was a bit more sinister, however. They cheered his every move as if to say that anyone – even Gomes – was better than Wiese between the sticks. Gomes didn't cover himself in glory before Max Kruse's opener after only four minutes but was happy to see Kevin Volland strike twice at the other end to secure an important 2-1 win over Freiburg.

• The battle of the Benders (Lars v Sven) in the BayArena saw a masterclass from Robert Lewandowski. The Polish international set up Marco Reus's goal with a perfect reverse pass, won two penalties – Blaszczykowski converted one and missed one, then scored the third to kill off Leverkusen's spirited fightback in the second half. The game was an excellent advert for the league. The champions are back in second spot following this win. "We are very proud, Leverkusen are incredibly strong," said Jürgen Klopp.

• Dortmund, one or two defensive wobbles notwithstanding, are in championship-winning form. It's come a little too late, however. Bayern turned in another win without conceding goal, their third since the winter break, to defend their 12-point advantage. The 3-0 scoreline away to Mainz (Thomas Müller, a brace from Mario Mandzukic) was slightly flattering, Thomas Tuchel's side had been pretty good in the first half. But after Müller's goal Bayern exerted imperious control. "You can't play much better than we did in the second half," said the CEO, Karl-Heinz Rummenigge. Serial irritant Matthias Sammer still managed to get upset, naturally, this time with the fourth official and Tuchel. "I don't remember any sporting director coming to the byline so often and verbally attacking me as well," Tuchel said angrily.

• An altogether different complaint was voiced by Uwe Seeler. The Hamburg icon, 76, is upset that his grandson Levin Oztunali, 16, is moving from Hamburg to Leverkusen at the end of the season. "This is very poor, what has happened there," Seeler said, "this has nothing to do with money, I know the background. The sporting director should be careful with his statements." Frank Arnesen said that Oztunali had had a choice between "family and education or money". The teenager will reportedly earn three times as much (€340,000) at the Bay-Arena.

Results: Bremen 2-0 Hannover, Schalke 1-2 Fürth, Wolfsburg 1-1 Augsburg, Hoffenheim 2-1 Freiburg, Mainz 0-3 Bayern, Hamburg 0-2 Frankfurt, Düsseldorf 3-1 Stuttgart, Nürnberg 2-1 Gladbach, Leverkusen 2-3 Dortmund.

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