On November 26, 1946, Montgomery defended his NYSAC World Lightweight Title against Wesley Mouzon in an eighth-round knockout at Convention Hall in Philadelphia, Pennsylvania before a substantial crowd, of 12,416. Surprisingly, he had just lost to Mouzon by knockout in a non-title bout only three months previously on August 19, 1946 at Shibe Park in Philadelphia. In their fiercely fought November title match, Mouzon took the first three rounds with speed and jabs, but Montgomery countered with body blows and rights, before ending the bout 2:18 into the eighth with a long left hook. Mouzon took a serious lacing throughout all but the first round, and had a serious injury to his right eye.