Borussia Dortmund Transfer News and Rumours Tracker: Week of December 16

As the winter break approaches, Borussia Dortmund have remained mum on any transfer activity. When asked in interviews and press conferences about potential signings in recent weeks, coach Juergen Klopp, sporting director Michael Zorc and CEO Hans-Joachim Watzke have essentially either claimed the club has no particular interest in making additions to the squad in January or they have declined to comment altogether.

However, like any club, Dortmund are surely monitoring the market and preparing for players to come and go. With Robert Lewandowski leaving the club on a Bosman in the summer, Dortmund will need to make changes. After all, considering their trouble with injuries this season, BVB are surely looking to add depth sooner or later.

Click "Begin Slideshow" for a look at all the players linked with a move to and from Dortmund in recent days.

—LAST UPDATE: Thursday, December 19— 

Mitsuru Maruoka

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Reports emerged late on Wednesday that Japanese talent Mitsuru Maruoka was set to join Dortmund, and on Thursday the club confirmed the 17-year-old's signing.

Maruoka will leave Cerezo Osaka, the same club that sold Shinji Kagawa to Dortmund in 2010 for just €350,000. A talented midfielder, Maruoka will remain at BVB on loan until the end of the 2014-15 season.

Dortmund confirmed that the loan agreement includes an option to buy for an undisclosed fee. The club also stated that Maruoka can initially expect to compete for playing time in the club's reserve team in the 3. Liga.

Kevin Volland

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In the same Bild report that claimed Dortmund were close to an agreement with Ji, it was also asserted that the Ruhr side are interested in signing Kevin Volland.

The 21-year-old Volland has had a very impressive season with Hoffenheim thus far, scoring seven goals and assisting four more in the Bundesliga. His most recent strike was against BVB over the weekend, so Juergen Klopp is well aware of the quality the Marktoberdorf native brings to the table.

Dortmund were linked with a move for Volland in TZ in May, and since then the player's stock has only risen. A recent report from the Mirror claimed that five Premier League clubs—Arsenal, Liverpool, Manchester United, Chelsea and Tottenham—are keen to sign the player.

In order to complete Volland's signing, BVB would seem to have their work cut out. 

UPDATE, December 19:

Bild reports that Dortmund's top candidate to replace Robert Lewandowski is Volland and despite great interest from other parties, BVB are fully committed to their goal of signing the Germany Under-21 international, whose contract with Hoffenheim expires in 2017.

Adrian Ramos

Although the report made clear that Volland is Dortmund's first priority, Bild claimed that Adrian Ramos is a possible signing for Juergen Klopp's side should they not be able to secure the Germany Under-21 international.

The Colombia international has been in fine form for Hertha this season, scoring 10 goals. And he will have the chance to show his class this weekend as Hertha visit Dortmund.

The report claimed that should Ramos (whose contract expires in 2015) opt not extend his contract, Hertha will be willing to sell him. Transfermarkt rates his value at €4 million as of June 30, 2013.

Diego Costa

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In the same report from Bild that claimed BVB's interest in Volland and Ramos, Diego Costa was also linked with a move to the Ruhr area.

According to the report, Volland or Ramos would be signed as added depth (the former especially would be capable of starting in any of the front four positions) and versatility in front of goal, while Robert Lewandowski's true successor would be a superstar striker—and Costa was mentioned as a top candidate.

Last month, Sport Bild reported that Costa had a €24 million buyout clause that BVB were willing to offer to Atletico Madrid for his release. The striker is well known around Europe, however, and if they are to land him Dortmund will surely have to fend off substantial competition.

Jackson Martinez

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Alongside Diego Costa, the other top striker candidate Bild mentioned in its Thursday report was Jackson Martinez. The 27-year-old is under contract at Porto until 2016, but reportedly has a buyout clause of approximately €38 million.

As with Costa, Martinez is a big star and is sure to garner offers from multiple top clubs. It will be an uphill battle for Dortmund to acquire his services, but it seems BVB are spreading their net wide and aiming high.

Michal Kadlec

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It's been just half a year since Michal Kadlec left Bayer Leverkusen for Fenerbahce, but the 29-year-old could be on the move back to the Bundesliga in the near future.

Citing a report from Turkish source Sabah, Germany-based media outlet Spox quoted Miroslav Kadlec, the player's father as saying: "The Dortmund rumors are not speculation. Our discussions are very advanced and are going very well."

Kadlec, who has only been used in the Turkish Super Lig for 48 minutes this season, is reportedly close to agreeing to a loan that would see him move to Dortmund for the second half of the season. According to the report, he will have a €3.5 million purchase option after its end.

A versatile defender, Kadlec is capable of playing on the left and in the center of defense. He therefore would be a useful option in what has been an injury-plagued Dortmund defense.

UPDATE, December 18:

Bild has claimed that Kadlec's father denied the quotes from Sabah. The German tabloid did not, however, quote Miroslav.

Dong-Won Ji

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Things have not gone entirely well for Dong-Won Ji since the player's move from Chunnam Dragons in his native South Korea to Sunderland in 2011. The striker has scored just two goals in 23 appearances in the Premier League.

Deemed surplus to requirements at the Stadium of Light, he was loaned to Augsburg in January. While given more minutes to show his ability, the Jeje native scored just five goals.

Juergen Klopp nonetheless seems to be a fan of the 22-year-old, who was linked with a move to Dortmund in May. According to the Sunderland Echo, the clubs weren't able to come to an agreement as to Ji's value at the time.

Ji nonetheless remains a favorite to Klopp, according to a report from Bild, and the player allegedly is keen to return to the Bundesliga.

The report claims Ji, who is out of contract in the summer, has agreed to terms on a move to BVB. However, his signing will only be officially announced in January.

It is speculated that a move in January for a modest transfer fee is possible, but whether Dortmund are willing to pay for a player they could get for free remains uncertain. 

UPDATE, December 17:

Mirror has corroborated the Bild story. The English source added comments from Sunderland coach Gus Poyet, published in the Sunderland Echo, stating that the player is indeed a surplus to requirements and cannot expect much playing time with the Premier League side in the coming months:

"[Ji is] a very good player, but I need to find the opportunities to say to him:'‘Here you go. Don’t try to think too much about how we’re playing, just go out there and play.'"

"But I don’t know how to play him because that’s what he needs."