 After college, he played for the Green Bay Packers of the National Football League (NFL) from 1935 to 1937, helping them win the 1936 NFL championship as their starting left halfback.Sauer left professional football in 1937 and coached at the University of New Hampshire from 1937 to 1941, compiling a record of 22-18-1.He left his coaching position and enlisted in the U.S. Navy in 1942 and was commissioned as an officer after completing the requisite training.