Ilkay Gundogan
Ilkay Gundogan has started 21 Bundesliga games this season after missing much of the last campaign due to injuryReuters

Manchester United may suffer a big blow in their hopes to sign Ilkay Gundogan after reports in Spain revealed the Borussia Dortmund star has passed a medical with Barcelona ahead of a potential move to the Camp Nou.

Dortmund sporting director Michael Zorc revealed earlier in May that they are ready to sell Gundogan at the end of the current campaign for a reasonable price in order to avoid losing him for free when his contract expires in summer 2016, after the player confirmed his decision not to renew his contract.

"Our negotiations with the player came to the conclusion that he is not going to extend his contract and so he will leave this summer. But this also will depend on what offers we have on the table. Until now we have not received any offer," Zorc said earlier in May.

Arsenal and Manchester United have reportedly been attracted by the situation, with Old Trafford manager Louis van Gaal recently earmarking the signing of a midfielder to replace Michael Carrick as a top priority for the summer.

"It's clear that Carrick is very important but that's also because we have only one right-sided holding midfielder. That's what I am saying already in the whole of the season, that our selection is not balanced, and I want to restore that in the next transfer period," the United manager said.

But earlier in May, AS reported the Premier League giants would face competition from Barcelona to secure the player's services. Now Mundo Deportivo has revealed Gundogan passed a medical with the La Liga giants ahead of a potential move to the Camp Nou.

Barcelona's interest for Gundogan is not new. The Catalans tried to sign him two seasons ago and in the summer of 2014 but decided to back-track due to concerns about his long-term back problems.

The 24-year-old was out of action for more than a year and missed all of last season due to a mystery spinal problem he suffered during a friendly between Germany and Paraguay in summer 2013.

So, according to reports, Barcelona have given him a medical to determine his fitness before launching a bid to Dortmund to secure his services.

Mundo Deportivo claims the medical was satisfactory – Gundogan has already played this season without any problems – and Barcelona have reached a pre-contract agreement with the player regarding a future move.

Nevertheless, with the La Liga champions unable to add any players this summer due to a transfer Fifa ban, the Catalan side will need to agree terms with Dortmund ahead of the January transfer window or wait until summer 2016 to get him as a free agent.

Should the reports be true, Gundogan will be expected to fill the void of Xavi Hernandez, 35, after the club legend, on 21 May, announced he will leave Barcelona – a club he has been at for his whole career – at the end of the season to play for Qatar side Al Sadd.