With the European transfer window opening up again on January 1, TSN.ca takes a daily look around the soccer world at the latest rumours and reports heading into what is sure to be another busy period of transactions.

Welcome Mats?

Manchester City is the latest team to be linked to Borussia Dortmund defender Mats Hummels. The German international is a wanted man in the BPL and the Daily Express reports that the defending champions are looking to the 25-year-old to help assuage issues in the back. City captain Vincent Kompany picked up an apparent hamstring injury during Saturday's 1-0 victory over Leicester City, while Matija Nastasic could be in line to link up with former manager Roberto Mancini at Inter.

Hummels won't come cheap, though, with reports that Dortmund, struggling mightily in the Bundesliga this season and currenly 16th in the the table, have placed a £47 million price tag on the defender.

Arsenal, still without Mathieu Debuchy, Laurent Koscielny and Nacho Monreal, and Manchester United, decimated with injuries to their defence, have also been linked to Hummels in recent months.

Adding Adnan?

With minutes becoming scarce at Old Trafford, Manchester United manager Louis van Gaal is reportedly interested in sending teenage winger Adnan Januzaj out on loan so that the Belgian international can get in some more first-team playing time.

The Daily Star reports that Inter's Roberto Mancini is interested in bringing in an attacking player in January and Januzaj could fit the bill. Januzaj's former manager, David Moyes, is also reportedly keen on bringing Januzaj to play under him again at Real Sociedad.

Januzaj, who made his international bow with Belgium in the lead-up to last summer's World Cup, has made only nine league appearances for United this season and has yet to score. In 27 league games last year, Januzaj scored four times.

An American in Germany?

Werder Bremen is desperate to kickstart its offence and is reportedly looking at Sunderland's American international Jozy Altidore for help.

According to the Sunderland Echo, the Bundesliga basement-dwellers are sounding out a move for the 24-year-old, despite the fact that Altidore, himself, is almost as goal-starved as Bremen is. Recently returning to manager Gustavo Poyet's first-choice starting XI after a spell relegated to the periphery, including in Saturday's 1-1 draw with West Ham, Altidore hasn't found the score sheet for the Black Cats in over a year.

Even with Altidore's poor form, Bremen might not be Altidore's only suitor. Ligue 1 side Lille is also reportedly interested in his services.

It is believed that Sunderland values the player in the £7 million range.