Borussia Dortmund have completed the signing of young AIK star Alexsander Isak on a 'long-term' contract, stealing him from under the noses of reigning European champions Real Madrid. 

The German club confirmed the move on their official channels on Monday morning, with sporting director Michael Zorc saying: "Alexander Isak is a high-caliber talent, who was wanted by numerous European top clubs. We are very glad that he has decided on Borussia Dortmund. BVB is just as convinced as the player is that this transfer is one with great potential."

Isak's AIK teammate Dickson Etuhu hinted at the transfer earlier in the day, posting a picture of the youngster signing a contract on his Instagram account. 

The picture was sent out to Etuhu's 17,000 followers with the caption: "True quality is recognised very early. Dortmund have incredible young players. Glad we had the chance to play together, and go become the top player we all believe you will be."

​ESPN FC report that the deal is set to earn the Swedish side somewhere in the region of £8.2m. Real Madrid were initially thought to be Isak's destination, but Dortmund's recent focus on bringing youth players into the first team - with Ousmane Dembele one of the biggest success stories of late - is thought to have swayed his decision. 

Isak's contract at the Westfalenstadion is expected to run until 2022 as the club look to tie down the long term future of one of the hottest prospects in European football. 

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