 Rosen made his debut on the professional league level in the Bundesliga for Eintracht Frankfurt on 20 February 1999 when he came on as a substitute for Frank Gerster in the 86th minute in a game against TSV 1860 München.While being under contract in Frankfurt, Rosen has been on loan with FC Augsburg and VfL Osnabrück.After his return to Frankfurt he played in three more matches in der 2.