Career
Grün began his career with FV Karlstadt, before in summer 2002 he was scouted by Football Club Bayern Munich. After three years in Bayern"s youth setup he was promoted to the reserve team, where he served as the backup goalkeeper for four years, behind Michael Rensing and later Thomas Kraft. After seven years with Football Club Bayern he left the Bavarian capital to sign a one-year contract with on 5 August 2009.