After seeing more of their stars in Tweets and photos emanating from the club's treatment room in the past few months, the vision of , Henrikh Mkhitaryan and lining up on the field of play at the RheinEnergieStadion may have been mistaken for a mirage.
Worst start since 2007/08
Even the return of their star trio could not prevent the five-time champions from their fifth defeat, however, as the club's worst start to a season since 2007/08 saw Dortmund slip to 14th in the Bundesliga standings.
Head coach Jürgen Klopp not being one to look for excuses anyway, the 47-year-old gave an honest account when asked about the reasons for Borussia's current domestic struggle. "We've got to get rid of our mistakes - not tomorrow, not the day after but immediately," he said after the game. "We just made things too easy for our opponents."
Full-strength, same mistakes
As was the case after Dortmund's previous four defeats in the Bundesliga, though, it was not easy to put a finger on precisely what had gone wrong, with statistics continuing to show Dortmund as the most potent side in the division in terms of shots at goal.
"It was pretty much the same story as in recent weeks. I get the feeling we're just lacking that little something in all areas," said sporting director Michael Zorc. "We're missing incision up front and at the back, we're gifting goals and the leading players are committing cardinal sins."
Champions League boost?
Needless to say, Reus and Co. will need more time and games to return to full fitness, although the Germany attacking midfielder had more shots on goal than the entire Köln team put together. Reus only started because Erik Durm was injured before kick-off, Gündogan was back after a 14-month absence and was equally short of match practice.
Fortunately for Dortmund, however, they return to Champions League action on Wednesday - a competition in which they've enjoyed far more success so far this season. A win against Galatasaray AS would see BVB with more points in three European fixtures than they have accumulated in eight domestically, and serve as a welcome boost for their upcoming Bundesliga clash with Hannover 96.