The Bundesliga champions have disappointed so far in the Champions League, and now need a big win to show their stars that they can succeed in the Ruhr area in the long term.It would be an understatement to say that Borussia Dortmund’s long-awaited return to the Champions League has been a disappointment. With four matches gone, the Bundesliga title holders are third in Group F, and on the verge of elimination.Qualification for the knockout rounds is almost impossible now: BVB will, in all likelihood, have to win their last two games, the second of which will have to be by a two-goal margin against a Marseille side that will by that point be content to settle even for a narrow loss. But that is another discussion for a later date: Dortmund have to take things one step at a time, and on Wednesday that first step will be a trip to England to visit Arsenal.The match at the Emirates will be BVB’s toughest international contest in nine years, and is absolutely a must-win game for Jurgen Klopp’s men, for reasons that exceed the scope of the 2011-12 Champions League. Indeed, on Wednesday, Dortmund are playing for their long-term future.Rising stars will often go unnoticed if they exit European competition early, but in Dortmund’s case, their best players are well known. Mario Gotze is their most coveted star, but others, like Mats Hummels and Neven Subotic, have caught the eye of several among Europe’s top clubs. And several more, like Shinji Kagawa, Kevin Grosskreutz, Lukas Piszczek and Sven Bender, could soon be on the radar of such big teams.In the past, BVB were able to retain their stars: in August, they rejected a bid in excess of €30 million for Gotze, and previously they turned down approaches from Chelsea and Bayern Munich for Subotic and Hummels, respectively. But they had the faith of their players, who at the time believed in the team’s long-term potential, and that the Signal Iduna Park was a suitable destination to support their ambitions, at least for the short-term. Gotze and Hummels both extended their deals over the course of last season, and the former’s agent exclusively told Goal.com in August that his client would stay in the Ruhr area for another two years. Players grow faster than clubs, though, and there will come a day when the likes of Gotze follow in the footsteps of Nuri Sahin as they leave the Ruhr area. But whether that day comes in eight months or 20, or more, depends on how Dortmund perform.BVB have another 21 Bundesliga games left to secure a top-four finish, but regardless, their qualification for the 2012-13 Champions League will be of little comfort if their stars feel they will only be sent to an early exit once more.In September, Dortmund battered Arsenal at the Westfalenstadion, but poor finishing and one woeful individual error saw them only narrowly escape with a point. On Wednesday, they have one more chance to prove themselves against an elite team, but it is an early final: there is no more room for silly errors, there are no more make-up matches. BVB absolutely must show their best form on Wednesday: their future depends on it.