Borussia Dortmund's ascent to the top of the European game has been built on the unlikely. When they were meant to lie down and be beaten, they proved everyone wrong. And yet, now that they have cemented their status as one of the continent's most feared opponents, they struggle to live up to the standards they have set themselves.
Ever since Jurgen Klopp took over in 2008, they've been producing surprises. Fans could scarcely believe the run of one defeat in seven months which proved the catalyst for their title win of 2010-11 and when it looked like order had been restored and Bayern Munich held a healthy Bundesliga lead the following year, they were able to turn the table on the Bavarians and retain their crown.
It has been a brilliant, romantic story, but there has always been one obstacle standing in the way of their seemingly unstoppable progress: themselves.
When they were expected to announce themselves on the European stage two years ago, they buckled under the pressure of being one the most eagerly-anticipated teams in the Champions League.
The following term, when drawn into a deadly group, they went the distance, losing heroically in the final, only struggling against Malaga, the only team they played whom they were expected to beat comfortably. Winning a third straight Bundesliga title, as many predicted they would, proved too much for them.
It's an issue that shows no signs of going away. It was no more in evidence than against Arsenal on Wednesday. Having claimed a plucky victory over the Gunners a fortnight ago in London, they were expected to take a stranglehold over the Champions League Group of Death, but they were oddly rash in the attacking third, snatching at shots and their final balls.
|MATCH FACTS | Dortmund 0-1 Arsenal
Henrikh Mkhitaryan and Marco Reus were particularly culpable of missing easy chances and Arsenal, who have kept just three clean sheets in the league this term, were able to enjoy a relatively easy evening against Dortmund, who managed to place just three of their 15 shots on target.
In the end, a horrible passage of defending, with centre-backs Neven Subotic and Sokratis Papastathopoulos particularly culpable, cost them as Arsenal scored with their first meaningful effort of the game.
It could well prove costly. In three weeks' time, they have a winner-takes-all game with Napoli and if they fail to win and Arsenal beat the group's whipping boys Marseille on home turf, they will face a humiliating early Champions League exit.
After the game, Klopp acknowledged that his side were at the usual level. "We simply did not convert our chances. We did not turn our good chances into guaranteed goals. In the end, we were not focused enough and not clinical enough," he said. Simply put, they bottled it in a key match.
For a club who stand on the threshold of the European elite, it would be disastrous. The club have made painstaking efforts to increase their profile across the continent over the last year or so - they've played the underdog, but want to be seen among the big boys.
For now, their Champions League fate remains in their hands, but they have to start doing the business in the big games they are expected to win. Arsenal deserve credit for a brave performance but Dortmund have to question why they were unable to convert their dominance into a victory.
By the time Napoli travel to Germany on November 26, they must have rectified their problems.
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