Nils Petersen has completed a permanent transfer to Werder Bremen on a four-year contract for an undisclosed fee.
Ozkan Yildirim has signed a new contract to keep him at Werder Bremen until 2016.
Manchester City defender Dominic Oduro has joined AGF Aarhus on an 18-month loan deal following a successful period on trial.
The 18-year-old, who has yet to play for City's first team, will gain valuable experience for the Superliga side who currently lie in 6th position.
The Premier League champions have a link to the Danish club through youth team coach Scott Sellars, who played for the club in 2001.
Meanwhile, Oduro could be joined in the Superliga by team mate Mohammed Abu.
The 21-year-old midfielder is reportedly about to join champions Nordsjaelland on loan.
The midfielder has spent the first half of the season in La Liga with Rayo Vallecano but could now be on his way to Denmark to help Nordsjaelland close the gap on FC Copenhagen at the top of the table.