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Late Wednesday night, Bild published a report claiming that Manchester United had made an offer to Robert Lewandowski, and that the Dortmund striker was likely to accept the English giant's approach.

The 24-year-old would earn €5 million per season over the duration of a five-year contract, provided Dortmund release him for a fee of around €22 million.

Whether United's offer is current is far from certain, given their abundance of striker talent that includes Wayne Rooney, Robin van Persie, Javier Hernandez and Danny Welbeck. And some have cast doubt on the legitimacy of the report, claiming the source was Lewandowski's agent.

Regardless, the Poland international's outstanding performances over the last 18 months have made him one of Europe's most coveted strikers. And with his contract set to expire in 2014, he is also one of the most available.

Should Lewandowski opt not to extend his contract before the summer, Dortmund can sell him for a modest fee. This is something that CEO Hans-Joachim Watzke has claimed is a real possibility. However, if BVB do eventually sell Lewandowski, it will be a catastrophic mistake.

Strikers like Lewandowski are hard to come by. He's a very specific type of player—a tremendously hard worker with power and pace to burn and a record of being good for 30 or more goals per season. BVB won't be able to find a replacement with his particular skill set, and any new signing cannot be assumed a certainty to hit the ground running.

The Ruhr side cannot afford a slow start in 2013-14, lest they lose the Bundesliga title race in the opening months for a second consecutive season and/or face an early exit in the Champions League. The benefit Lewandowski brings on the international stage should be enough to justify a hefty raise. And it's a raise BVB can certainly afford.

For now, Dortmund's stars are on relatively low wages. Mario Goetze and Marco Reus earn €4.6 million and €4 million per year, respectively, so to match United's alleged €5 million offer would hardly be out of the ordinary for BVB. And given that Dortmund have been raking in record profits (€34.3 million after taxes during the 2011-12 season) and are expected to earn even more in 2012-13 due to improved Champions League performance, they can easily afford €5 million or more if need be.

And need there is—not only for sporting reasons, but for the club's image and sustainability.

While Dortmund's record of rejecting offers for their stars and convincing players to sign contract extensions is commendable, the fact remains that they are selling key players at a rate of one per season. First it was Nuri Sahin, then Shinji Kagawa. Now Neven Subotic, Marcel Schmelzer and Lewandowski are the only starters left with contracts expiring in 2014.

Subotic is closing in on an extension to 2016, while Schmelzer is currently in negotiations and "cannot imagine anything better" than Dortmund. That leaves Lewandowski, who may opt not to extend his stay.

Even so, Dortmund have all the power to deny him a transfer. And if they do, it will end the dangerous trend that cost them two world-class midfielders in consecutive seasons.

If Lewandowski leaves this summer, Ilkay Gundogan and/or Jakub Blaszczykowski may follow him in 2015, Goetze in 2016 and Mats Hummels and/or Marco Reus in 2017. Putting all their echte liebe aside, BVB will still have the same "small club" feel about them that has been the downfall of teams like Arsenal and, drawing a Bundesliga comparison, Hamburg.

Both the London side and HSV have done some very lucrative business on the transfer front in recent years, but neither will win any major titles anytime soon. For Dortmund to continue to sell would equate to sporting self-destruction.

Watzke and Michael Zorc could take a lesson from the Bayern Munich playbook when it comes to handling Lewandowski's situation. The Bavarians were prepared to hold onto Franck Ribery in 2010 when he had just a year remaining on his contract, and many suitors very much interested in his signature. They advanced to the Champions League final, however, and the Frenchman extended just before the summer transfer window opened.

Whether Bayern were bluffing or would have sold Ribery had he not extended his stay will forever be a mystery, but their domestic double and progress to the final of Europe's most elite tournament certainly sweetened their offer. Dortmund can convince Lewandowski that they are a big enough club for him by advancing far in the Champions League and taking an uncompromising stance to deny him any summer move.

If BVB refuse to sell, they stand to lose €22 million in transfer fees but retain a world-class striker for at least another season—another season in which they may be able to convince Lewandowski that his future is in the Ruhr area, not Manchester or elsewhere. Another season in which their team, a proven unit, can convince other big stars to move to the Signal Iduna Park.

It's a gamble, but Dortmund have the money to offer the striker a great deal or even to let him leave on a free transfer if it comes to that. Eventually BVB will have to put their feet down if they are to establish themselves permanently as a big club.

With the future of a player as irreplaceable as Lewandowski still in the balance, that time is now.

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