 He was a key member of the Strasbourg team that finished second in the 1934–35 Championship and reached the final of the cup in 1937.When Alsace was "de facto" annexed by the Third Reich, Fritz Keller elected to play for SS side SG SS Straßburg in the Gauliga Elsaß rather than continuing with RC Strasbourg's ersatz, Rasensport Club Straßburg.According to some of his former teammates at RCS, this was more an opportunistic move than a real ideological gesture as the SS were offering significant rewards to build up the best team in Alsace.