Career
Zahner began playing professionally in 1976 with his local club, Football Club Aarau. In 1982, he made the step up to Football Club Zürich but failed to cut it and left for Football Club Zug after just one season. He returned to Football Club Aarau in 1984 and played there for another three years before moving on to Football Club Basel and retiring in 1988.
After his retirement from playing, he coached the Swiss under-17s team from 1991 until 1999.
In 2006, he became the assistant manager of Football Club Aarau and was eventually appointed manager in 2007. He lasted only a short while in charge, however.