An injury-ravaged Borussia Dortmund face leaders Bayern Munich on Saturday in the Bundesliga’s version of “el clasico” in a crucial few days for the club.

Dortmund lost central defender Mats Hummels and left-back Marcel Schmelzer to injury playing for Germany on Tuesday, and are now without the entire back four which featured in May’s Champions League final defeat to Bayern.

Central defender Neven Subotic recently ruptured his cruciate knee ligament, while right-back Lukasz Piszczek also continues to be sidelined. Midfielder Ilkay Gundogan, out since August with a back problem, is another key player missing.

While Spain has its traditional “clasico” of Real Madrid versus Barcelona, Dortmund against Bayern has developed over the past years into a similar heavyweight battle to electrify German fans.

Bayern, spurred on by Dortmund’s two title victories in 2011 and 2012, hit back last season with the treble — including the Champions League title in the all-German final — and with a record 37 games without defeat are threatening again under coach Pep Guardiola to steamroller all in front of them.

Second-placed Dortmund, now four points behind, desperately need a win — or at least not lose — to avoid their rivals running away. Four days later they visit Napoli in the Champions League — a defeat against the Serie A side and they are as good as out.

Dortmund’s acknowledged relative lack of depth compared to Bayern has been exposed by their latest injury misfortunes. The club has responded by signing 34-year-old defender Manuel Friedrich, who has been without a club since leaving Bayer Leverkusen in the summer.

Friedrich, a former Germany international, is expected to go straight into central defence alongside Greece defender Sokratis Papastathopoulos.

“We will have to improvise,” Dortmund sports director Michael Zorc told Kicker magazine.

Despite his injury problems, coach Juergen Klopp knows his side are an almost irrepressible force at home, and after six wins out of six in the league could set a club record with a seventh victory against Bayern.

Bayern won’t need reminding that their last away league defeat was at Dortmund’s Signal Iduna Park, in April 2012, when Robert Lewandowski scored in a 1-0 victory.

“We don’t ever raise the white flag before anyone. We have shown many times that we can beat Bayern,” Zorc said.

Bayern defender Jerome Boateng says he and his team-mates will have to be “really wide awake” from the word go.

“Dortmund are really strong at home and we mustn’t make any simple mistakes. They are the best counter-attacking team and are merciless in punishing mistakes,” he said.

The match will also see the return of midfielder Mario Goetze, who shocked Dortmund fans with his 37-million-euro (49.7-million-dollar) move to Bayern at the end of last season, a transfer record for a German player.

Not all Dortmund fans have forgiven him the move, and the 21-year-old international, who had been with Dortmund since he was nine, could receive an uncomfortable reception if he plays.

“I appeal to the fairness of our fans,” Zorc said.

“We are not naive to believe there will be a standing ovation for Mario. However he played successfully and well for us for 12 years, and we received a record transfer sum for him. All these things should be taken into consideration Saturday.” The Dortmund-Bayern duel overshadows the rest of the programme, but there are plenty of attractive fixtures, including third-placed Bayer Leverkusen’s trip Saturday to surprise package Hertha Berlin.

On form Wolfsburg — with four straight wins — are at tail-enders Nuremberg, who are still without a victory, in a first return to his old club for Wolves coach Dieter Hecking.

Sixth-placed Schalke are at struggling Eintracht Frankfurt, Eintracht Braunschweig host Freiburg in a meeting between two teams in the relegation zone, and Augsburg welcome Hoffenheim, while on Sunday SV Hamburg take on Hanover, and Werder Bremen greet Mainz.

The weekend programme begins Friday evening when VfB Stuttgart face visiting fourth-placed Borussia Moenchengladbach.

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