Career
He last played for Football Club Concordia Basel. He has also appeared in the squad four times for the Switzerland national football team, but played only twice. On the 18 June 2009 he retired from professional football due to his reoccurring injuries.
Muff began in the youth program of Grasshopper Club Zürich in 1997, and was transferred to Football Club Basel on a four-year contract in 2000.
After one year in Basel, Muff was aggressively loaned in 2001 to Football Club Lucerne and Air Corps Lugano, before he returned to Basel. He was again on loan for the year 2002 to Football Club Lucerne and then loaned to Football Club Zürich in 2003.
When his Football Club Basel contract expired over summer 2004, Grasshopper Club Zürich signed Muff for €1 million, bringing him back to the club where his career began. While on loan to Football Club Lucerne, Muff played on the host Switzerland national under-21 football team in the 2002 European Under-21 Football Championship wearing the number 21 shirt.