Munich - It was June 2013: the dust was beginning to settle on a season which, had it not been for FC Bayern München, would have been the most successful in Borussia Dortmund’s rich history.

A Bundesliga title, DFB Cup glory for the second year running and a UEFA Champions League title for the first time since 1997: the bounty was within touching distance - but the red half of Munich had other ideas.

Defensive reinforcements


In truth, it was the Bavarians who earned the aforementioned trio of crowns, beating Dortmund in both cup competitions, as well as the DFL Supercup, and leaving them second best in the league. What would have been a season to look back on with unprecedented joy was instead one of ifs, buts and maybes. Klopp knew exactly why.

BVB had let in too many goals - 17 more than in 2011/12 - and so Dortmund’s head coach duly sought out a summer remedy in . The plan seemed fool proof. The former SV Werder Bremen hero would keep and Neven Subotic on their toes and provide fresh legs over the course of a gruelling campaign.

Dropping like flies


Dortmund’s season, however, had not even started when they suffered their first setback as Lukasz Piszczek belatedly went under the knife to rectify a troublesome hip injury. Fortunately, Klopp was able to call on utility man Kevin Großkreutz to plug a hole he had filled in the past, allowing Dortmund to move swiftly on, confident the preceding season's ills had been resolved.

Sure enough, die Schwarzgelben stole an early, albeit narrow, march on Bayern, winning their first five league matches - but the smiles would not last. A season-ending knee injury to Neven Subotic was merely the precursor to far graver news: BVB would have to prepare for one of their biggest games of the season, der Klassiker, without defensive duo Mats Hummels and Marcel Schmelzer - both injured on international duty.

Improvisation in the Klassiker


As far as viable replacements are concerned, Erik Durm would ideally join Sokratis and Großkreutz in Dortmund’s makeshift back four. Even he could miss out on Saturday, though, after picking up a knee injury on duty with Germany’s Under-21s, while new recruit Manuel Friedrich suffered the same fate in midweek, leaving midfielder Jakub Blaszczykowski, 19-year-old Koray Günther, 18-year-old Marian Sarr and Oliver Kirch (31) as Klopp’s remaining candidates for a starting berth.

"We're disappointed that our entire back line from last year is out, but we've got to live with it," BVB’s CEO Hans-Joachim Watzke told Sport1. Dortmund only have to keep Mario Mandzukic, Franck Ribery, Arjen Robben, Mario Götze and Thomas Müller at bay after all. Three days later, Klopp’s patchwork XI must then beat SSC Napoli to keep their Champions League hopes alive. Clearly, BVB's current injury crisis could hardly have come at a more inopportune moment in the battle to dethrone Bundesliga and European kings Bayern.