Rohr, known primarily by his nickname "Ossi", began his career in the 1920s as a striker for hometown clubs
FC Phönix Mannheim and later for
VfR Mannheim. He was quickly marked as a talented striker with a natural instinct for scoring goals. Fueled by the desire to display his talents at a higher level, he signed with
FC Bayern Munich in 1930. In his first season with FC Bayern, Rohr and his teammates barely missed out on the final round of the German Championship. In his second season with the club, FC Bayern went on to defeat
Eintracht Frankfurt in the final and claim its first German Championship with a 2–0 victory. Ossi Rohr, who scored one of the two goals in the match against Eintracht, was German Champion at the young age of 20 years. The following year, Bayern's fortunes were significantly poorer, resulting in a mid-table finish within
Bavaria. This lackluster finish encouraged Rohr to continue his career elsewhere. At the age of 19, Rohr received his first
Germany national team call-up by German manager
Otto Nerz. There he found himself on the pitch with stars such as
Ernst Kuzorra and
Richard Hofmann. He played in a total of four national team matches through March 1933, receiving his first cap a year earlier against
Switzerland (2–0) in March 1932. He later scored two goals in a 4–3 win against
Sweden, one goal in a 1–3 loss to
Italy, and two goals in a 3–3 draw with
France. With five goals in four matches, Rohr looked to be on the verge of a very successful national career. ==Success Abroad==