 Complete the following phrase:  Mathy joined Bayern Munichs youth team in 1979, and made his first-team debut a year later, as a substitute for Norbert Janzon in a 31 win over VfL Bochum. He made two more substitute appearances in the 198081 season, replacing Dieter Hoeneß and scoring both times, as Bayern ended the season as German champions. The following season he made seventeen appearances without getting on the scoresheet, the last of which was the 